Random Access Method and Apparatus

ABSTRACT

A random access method includes working, by a user equipment (UE), on a first bandwidth part (BWP), where the first BWP is a currently active BWP, when the UE needs to perform a random access procedure, the UE performs the random access procedure on an initial BWP or on the first BWP, and when the UE receives BWP switching indication information from a network device instructing the UE to use a second BWP when performing the random access procedure on the first BWP, continuing, by the UE, to perform the random access procedure on the first BWP, or stopping, by the UE, performing the random access procedure on the first BWP, and performing the random access procedure on the second BWP.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 16/758,552filed on Apr. 23, 2020, which is a U.S. National Stage of InternationalPatent Application No. PCT/CN2018/112273 filed on Oct. 27, 2018, whichclaims priorities to Chinese Patent Application No. 201711023955.9 filedon Oct. 27, 2017 and Chinese Patent Application No. 201711395730.6 filedDec. 21, 2017. All of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to a random access method and apparatus.

BACKGROUND

A concept of a bandwidth part (bandwidth part, BWP) is introduced to anew radio (New Radio, NR) radio access network. When a bandwidth of acell is very high, UE (User Equipment) may work on only a part of thebandwidth of the cell. Each part of the bandwidth of the cell isreferred to as a BWP, as shown in FIG. 1. Each BWP correspondinglysupports one physical layer parameter, which may be referred to asnumerology (numerology). The numerology includes subcarrier spacingconfiguration and cyclic prefix length configuration. Different BWPs maysupport same numerology or different numerology.

In an NR mobile communications system, initially accessing a system bythe UE mainly includes three important steps: (1) an initialsynchronization and cell search process; (2) a network sends basicsystem information; and (3) a random access (Random Access, RA)procedure. How the UE uses a BWP when the UE needs to perform an RAprocedure is a problem that needs to be urgently resolved.

SUMMARY

Embodiments of this application provide a random access method andapparatus, to resolve a problem of how UE uses a BWP when the UE needsto perform an RA procedure.

The embodiments provided in this application include any one of thefollowing:

1. A random access method, applied to UE, where the method includes:working, by the UE, on a first bandwidth part BWP, where the first BWPis a currently active BWP; and when the UE needs to perform a randomaccess procedure, performing, by the UE, the random access procedure onan initial BWP if the first BWP does not meet a condition for performinga random access procedure; or performing, by the UE, the random accessprocedure on the first BWP if the first BWP meets a condition forperforming a random access procedure; and the method further includes:when the UE performs the random access procedure on the first BWP,receiving, by the UE, BWP switching indication information sent by anetwork device, where the BWP switching indication information is usedto instruct the UE to use a second BWP; and continuing, by the UE, toperform the random access procedure on the first BWP; or stopping, bythe UE, performing the random access procedure on the first BWP, andperforming, by the UE, the random access procedure on the second BWP.

In the method, the UE currently works on the first BWP, and when the UEneeds to perform the random access procedure, the UE can select, basedon whether the first BWP meets a condition for performing a randomaccess procedure, a BWP used to perform the random access procedure.Further, after the UE receives the BWP switching indication informationwhen performing the random access procedure on the first BWP, the UE canchoose whether to continue to complete the random access procedure onthe first BWP, or to switch to the second BWP to perform the randomaccess procedure, so as to ensure that the UE can complete random accessin a timely manner. Specifically, if the first BWP does not meet thecondition for performing a random access procedure, the UE may choose toperform the RA procedure on the initial BWP; or if the first BWP meetsthe condition for performing a random access procedure, the UE maychoose to perform the RA procedure on the currently active first BWP. Ifthe UE chooses to perform the RA procedure on the first BWP, and if theUE receives, when the UE performs the random access procedure on thefirst BWP, the BWP switching indication information (used to instructthe UE to use the second BWP) sent by the network device, the UE maycontinue to perform the random access procedure on the first BWP, or theUE may choose to switch from the first BWP to the second BWP to performthe RA procedure. The method provides a solution of how the UE uses aBWP when the UE needs to perform an RA procedure, so that the UE canquickly complete the random access procedure.

2. The method according to Embodiment 1, where the performing, by theUE, the random access procedure on an initial BWP includes: performing,by the UE, the random access procedure on the initial BWP if the initialBWP meets the condition for performing a random access procedure.

According to the method provided in this application, if the first BWPon which the UE currently works does not meet the condition forperforming a random access procedure, and the initial BWP meets thecondition for performing a random access procedure, the UE may choose toswitch to the initial BWP to perform the RA procedure, so that therandom access procedure is quickly implemented.

3. The method according to Embodiment 1 or 2, where the performing, bythe UE, the random access procedure on the second BWP includes:performing, by the UE, the random access procedure on the second BWP ifthe second BWP meets the condition for performing a random accessprocedure.

According to the method provided in this application, after the UEreceives the BWP switching indication information sent by the networkdevice, where the BWP switching indication information is used toinstruct the UE to use the second BWP, when the second BWP meets thecondition for performing a random access procedure, the UE may choose toswitch to the second BWP to perform the RA procedure. In this way, itcan be ensured that the RA procedure is successfully implemented.

4. The method according to any one of Embodiments 1 to 3, where themeeting the condition for performing a random access procedure includesat least one of the following two: a resource used for random access isavailable; or a common search space CSS used to receive a random accessresponse RAR is available.

According to the method provided in this application, if a resource usedfor random access is available (or is configured) in a BWP, the BWP maybe used to perform the random access procedure; or if a CSS is availablein a BWP, the BWP may be used to perform the random access procedure.

5. The method according to any one of Embodiments 1 to 4, where that thecondition for performing a random access procedure is not met includesat least one of the following two: no resource used for random access isconfigured; or no common search space CSS used to receive a randomaccess response RAR is configured.

According to the method provided in this application, if the resourceused for random access is not available in a BWP, the UE may quicklydetermine that the random access procedure cannot be initiated on theBWP, or if the CSS used to receive an RAR is not available in a BWP, theUE may quickly determine that downlink information cannot be received onthe BWP, so that the UE selects a BWP meeting the condition forperforming a random access procedure, to implement the random accessprocedure.

6. The method according to any one of Embodiments 1 to 5, where theperforming, by the UE, the random access procedure on the first BWPincludes at least any one of the following: skipping, by the UE,deactivating the first BWP; keeping, by the UE, the first BWP activated;stopping, by the UE, a bandwidth part inactivity timer used to maintainthe first BWP; continuing to use a value of a power ramping counter ofthe user equipment; continuing to use a backoff parameter of the userequipment; using, by the UE, a random access priority corresponding tothe first BWP, and adjusting at least one of the following based on atleast the random access priority corresponding to the first BWP: thebackoff parameter, a power increment value, the power ramping counter,and a preamble counter; continuing, by the UE, to use a first transmitbeam, where the first beam is a transmit beam used by the UE before orwhen the UE receives the switching indication information; andswitching, by the UE, from the first transmit beam to a second transmitbeam, where the second transmit beam is different from the firsttransmit beam.

According to the method provided in this embodiment of this application,a parameter setting of the UE is specified when the UE performs a randomprocedure on the first BWP. Specifically, in a possible implementation,the performing, by the UE, the RA procedure on the first BWP mayinclude: stopping, by the UE, the bandwidth part inactivity timer usedto maintain the first BWP. In this way, the following case can beprevented: when the UE performs the RA procedure on the first BWP,because the UE may need to switch to a default BWP if the bandwidth partinactivity timer continues to run, instability is caused to the RAprocedure currently performed on the first BWP.

In a possible implementation, the performing, by the UE, the RAprocedure on the first BWP may include: keeping, by the UE, the firstBWP in an activated state. In this way, consistency with a state machineof the UE can be ensured, to prevent inconsistent actions performed bythe UE in different states

In a possible implementation, the UE performs the RA on the currentlyworking first BWP, and may continue to use a parameter (for example, thevalue of the power ramping counter of the user equipment, or the backoffparameter of the user equipment) used before the RA is performed, so asto prevent impact of instability caused to a system by a change of theparameter of the UE device, and avoid interference to a network, andunfair contention.

In a possible implementation, the UE continues to use the first transmitbeam, so that an access procedure of the UE can be accelerated. Inanother possible implementation, the UE may switch from the firsttransmit beam to the second transmit beam, so that the UE obtains abetter reception gain.

7. The method according to any one of Embodiments 1 to 6, where thenetwork device configures a default BWP for the UE, the default BWPincludes a default downlink BWP, and the first BWP includes a firstdownlink BWP; and the first downlink BWP is different from the defaultdownlink BWP.

According to the method provided in this application, that the firstdownlink BWP is different from the default downlink BWP may be used todistinguish an object specific to a bandwidth part inactivity timer (ifthe UE currently works on the first bandwidth part BWP, the objectspecific to the current bandwidth part inactivity timer is the firstdownlink BWP), to prevent the bandwidth part inactivity timer from beingblindly started and/or stopped.

8. The method according to any one of Embodiments 1 to 7, where theperforming, by the UE, the RA procedure on the second BWP includes atleast any one of the following: setting, by the UE, the power rampingcounter to an initial value; setting, by the UE, the backoff parameterto an initial value, or setting the backoff parameter to a value in abackoff indicator; using, by the UE, a random access prioritycorresponding to the second BWP, and adjusting at least one of thefollowing based on at least the random access priority corresponding tothe second BWP: the backoff parameter, the power increment value, thepower ramping counter, and the preamble counter; continuing, by the UE,to use the first transmit beam, where the first beam is a transmit beamused by the UE before or when the UE receives the switching indicationinformation or before the UE switches to the second BWP; and switching,by the UE, from the first transmit beam to the second transmit beam,where the second transmit beam is different from the first transmitbeam.

According to the method provided in this application, the UE switches tothe second BWP to perform the RA procedure, the UE may initialize theused parameter, and the UE may not need to reserve the previously usedparameter such as the value of the power ramping counter or backoffparameter initialization, to avoid incompatibility with the previousrandom access procedure. The UE may continue to use the first transmitbeam, so that the RA procedure of the UE is accelerated; or the UE maychoose to switch to the second transmit beam, so that the UE obtains abetter reception gain. The UE performs the RA procedure on the secondBWP and performs one or more of the parameter settings of the UE, sothat the UE can better implement interworking, and the user equipmentimplements standardization of the random access procedure, to reduceimpact caused by the user equipment to the network.

9. The method according to any one of Embodiments 1 to 7, where theperforming, by the UE, the RA procedure on the second BWP includes atleast any one of the following: continuing to use the value of the powerramping counter of the user equipment; continuing to use the backoffparameter of the user equipment; using, by the UE, a random accesspriority corresponding to the second BWP, and adjusting at least one ofthe following based on at least the random access priority correspondingto the second BWP: the backoff parameter, the power increment value, thepower ramping counter, and the preamble counter; continuing, by the UE,to use the first transmit beam, where the first beam is a transmit beamused by the UE before or when the UE receives the switching indicationinformation or before the UE switches to the second BWP; and switching,by the UE, from the first transmit beam to the second transmit beam,where the second transmit beam is different from the first transmitbeam.

According to the method provided in this application, when the UEperforms the RA procedure on the second BWP, the UE continues to usesome original parameters, for example, continues to use the value of thepower ramping counter and the backoff parameter. In this way, impact ofinstability caused to the system by a change of the parameter used bythe UE can be prevented, interference caused to the network can beavoided, and unfair contention can be avoided. The UE continues to usethe first transmit beam, so that the random access procedure of the UEcan be accelerated. The UE switches to the second transmit beam, so thatthe UE can obtain a better reception gain, and the UE implementsstandardization of the random access procedure, to reduce impact causedby the UE to the network.

10. The method according to any one of Embodiments 1 to 9, where theperforming, by the UE, the RA procedure on an initial BWP includes atleast any one of the following: setting, by the UE, the power rampingcounter to the initial value; setting, by the UE, the backoff parameterto the initial value, or setting the backoff parameter to the value inthe backoff indicator; using, by the UE, a random access prioritycorresponding to the initial BWP, and adjusting at least one of thefollowing based on at least the random access priority corresponding tothe initial BWP: the backoff parameter, the power increment value, thepower ramping counter, and the preamble counter; continuing, by the UE,to use the first transmit beam, where the first beam is a transmit beamused by the UE before the UE switches to the initial BWP; and switching,by the UE, from the first transmit beam to the second transmit beam,where the second transmit beam is different from the first transmitbeam.

According to the method provided in this application, when performingthe RA procedure on the initial BWP, the UE initializes some usedparameters, for example, initializes the value of the power rampingcounter and the backoff parameter. In this way, the UE may not need tokeep the parameters, and incompatibility with the original random accessprocedure is avoided, so that the UE implements standardization of therandom access procedure, to reduce impact caused by the UE to thenetwork.

11. The method according to any one of Embodiments 1 to 10, where thefirst BWP includes a first uplink UL BWP and/or a first downlink BWP,and the second BWP includes a second uplink UL BWP and/or a seconddownlink BWP; that the BWP switching indication information is used toinstruct the UE to use the second BWP includes that the BWP switchingindication information is used to instruct the UE to use the seconduplink UL BWP; or the BWP switching indication information is used toinstruct the UE to use the second downlink BWP, or the BWP switchingindication information is used to instruct the UE to use the seconduplink UL BWP and the second downlink BWP; and the BWP switchingindication information is further used to instruct the UE to switch thefirst uplink UL BWP, or the BWP switching indication information isfurther used to instruct the UE to switch the first downlink BWP, or theBWP switching indication information is further used to instruct the UEto switch the first uplink UL BWP and the first downlink BWP.

According to the method provided in this application, the UE may switchto an indicated specific BWP based on different cases flexibly indicatedin the BWP switching indication information.

12. A random access apparatus, where the apparatus is user equipment UE,the UE includes a processing unit and a receiving unit, the UE works ona first bandwidth part BWP, and the first BWP is a currently active BWP;the processing unit is configured to: when the UE needs to perform arandom access procedure, if the first BWP does not meet a condition forperforming a random access procedure, enable the UE to perform therandom access procedure on an initial BWP; or if the first BWP meets acondition for performing a random access procedure, enable the UE toperform the random access procedure on the first BWP; the receiving unitis configured to: when the UE performs the random access procedure onthe first BWP, receive BWP switching indication information sent by anetwork device, where the BWP switching indication information is usedto instruct the UE to use a second BWP; and the processing unit isfurther configured to: after the receiving unit receives the BWPswitching indication information, enable the UE to continue to performthe random access procedure on the first BWP; or is further configuredto: after the receiving unit receives the BWP switching indicationinformation, enable the UE to stop performing the random accessprocedure on the first BWP and perform the random access procedure onthe second BWP.

13. The apparatus according to Embodiment 12, where when performing therandom access procedure on the initial BWP, the processing unit isconfigured to perform the random access procedure on the initial BWP ifthe initial BWP meets the condition for performing a random accessprocedure.

The processing unit and/or the receiving unit of the UE may performdetermining or detection, to determine whether a BWP meets the conditionfor performing a random access procedure; or the network device mayperform determining or detection, to determine whether a BWP meets thecondition for performing a random access procedure; or the networkdevice and the UE may separately perform determining or detection, todetermine whether a BWP meets the condition for performing a randomaccess procedure.

14. The apparatus according to Embodiment 12 or 13, where whenperforming the random access procedure on the second BWP, the processingunit is configured to: perform the random access procedure on the secondBWP if the second BWP meets the condition for performing a random accessprocedure.

15. The apparatus according to any one of Embodiments 12 to 14, wherethe meeting the condition for performing a random access procedureincludes at least one of the following two: a resource used for randomaccess is available; or a common search space CSS used to receive arandom access response RAR is available.

16. The apparatus according to any one of Embodiments 12 to 15, wherethat the condition for performing a random access procedure is not metincludes at least one of the following two: no resource used for randomaccess is configured; or no common search space CSS used to receive arandom access response RAR is configured.

17. The apparatus according to any one of Embodiments 12 to 16, wherewhen performing the RA procedure on the first BWP, the processing unitperforms at least any one of the following: skipping deactivating thefirst BWP; keeping the first BWP activated; stopping a bandwidth partinactivity timer used to maintain the first BWP; continuing to use avalue of a power ramping counter of the user equipment; continuing touse a backoff parameter of the user equipment; using a random accesspriority corresponding to the first BWP, and adjusting at least one ofthe following based on at least the random access priority correspondingto the first BWP: the backoff (backoff) parameter, a power incrementvalue, the power ramping counter, and a preamble counter (preamblecounter); continuing to use a first transmit beam, where the first beamis a transmit beam used by the UE before or when the UE receives theswitching indication information; and switching from the first transmitbeam to a second transmit beam, where the second transmit beam isdifferent from the first transmit beam.

18. The apparatus according to any one of Embodiments 12 to 17, wherethe network device configures a default BWP for the UE, the default BWPincludes a default downlink BWP, and the first BWP includes a firstdownlink BWP; and the first downlink BWP is different from the defaultdownlink BWP.

19. The apparatus according to any one of Embodiments 12 to 18, wherewhen performing the RA procedure on the second BWP, the processing unitperforms at least any one of the following: setting the power rampingcounter to an initial value; setting the backoff parameter to an initialvalue, or setting the backoff parameter to a value in a backoffindicator; using a random access priority corresponding to the secondBWP, and adjusting at least one of the following based on at least therandom access priority corresponding to the second BWP: the backoffbackoff parameter, the power increment value, the power ramping counter,and the preamble counter preamble counter; continuing to use the firsttransmit beam, where the first beam is a transmit beam used by the UEbefore or when the UE receives the switching indication information orbefore the UE switches to the second BWP; and switching from the firsttransmit beam to the second transmit beam, where the second transmitbeam is different from the first transmit beam.

20. The apparatus according to any one of Embodiments 12 to 18, wherewhen performing the RA procedure on the second BWP, the processing unitperforms at least any one of the following: continuing to use the valueof the power ramping counter of the user equipment; continuing to usethe backoff parameter of the user equipment; using a random accesspriority corresponding to the second BWP, and adjusting at least one ofthe following based on at least the random access priority correspondingto the second BWP: the backoff backoff parameter, the power incrementvalue, the power ramping counter, and the preamble counter preamblecounter; continuing to use the first transmit beam, where the first beamis a transmit beam used by the UE before or when the UE receives theswitching indication information or before the UE switches to the secondBWP; and switching from the first transmit beam to the second transmitbeam, where the second transmit beam is different from the firsttransmit beam.

21. The apparatus according to any one of Embodiments 12 to 20, wherewhen performing the RA procedure on the initial BWP, the processing unitperforms at least any one of the following: setting the power rampingcounter to the initial value; setting the backoff parameter to theinitial value, or setting the backoff parameter to the value in thebackoff indicator; using a random access priority corresponding to theinitial BWP, and adjusting at least one of the following based on atleast the random access priority corresponding to the initial BWP: thebackoff parameter, the power increment value, the power ramping counterpower ramping counter, and the preamble counter preamble counter;continuing to use the first transmit beam, where the first beam is atransmit beam used by the UE before the UE switches to the initial BWP;and switching from the first transmit beam to the second transmit beam,where the second transmit beam is different from the first transmitbeam.

22. The apparatus according to any one of Embodiments 12 to 21, wherethe first BWP includes a first uplink UL BWP and/or a first downlinkBWP, and the second BWP includes a second uplink UL BWP and/or a seconddownlink BWP; that the BWP switching indication information is used toinstruct the UE to use the second BWP includes that the BWP switchingindication information is used to instruct the UE to use the seconduplink UL BWP, or the second downlink BWP, or both the second uplink ULBWP and the second downlink BWP; and the BWP switching indicationinformation is further used to instruct the UE to switch the firstuplink UL BWP, or used to instruct the UE to switch the first downlinkBWP, or used to instruct the UE to switch the first uplink UL BWP andthe first downlink BWP.

23. User equipment UE, where the UE includes a transceiver, a processor,and a memory, where the memory is configured to store a computerexecutable instruction, the UE works on a first bandwidth part BWP, andthe first BWP is a currently active BWP; the processor is configured to:when the UE needs to perform a random access procedure, if the first BWPdoes not meet a condition for performing a random access procedure,enable the UE to perform the random access procedure on an initial BWP;or if the first BWP meets a condition for performing a random accessprocedure, enable the UE to perform the random access procedure on thefirst BWP; the transceiver is configured to: when the UE performs therandom access procedure on the first BWP, receive BWP switchingindication information sent by a network device, where the BWP switchingindication information is used to instruct the UE to use a second BWP;and the processor is further configured to: after the transceiverreceives the BWP switching indication information, enable the UE tocontinue to perform the random access procedure on the first BWP; or isfurther configured to: after the transceiver receives the BWP switchingindication information, enable the UE to stop performing the randomaccess procedure on the first BWP and perform the random accessprocedure on the second BWP.

24. The UE according to Embodiment 23, where when performing the randomaccess procedure on the initial BWP, the processor is configured toperform the random access procedure on the initial BWP if the initialBWP meets the condition for performing a random access procedure.

25. The UE according to Embodiment 23 or 24, where when performing therandom access procedure on the second BWP, the processor is configuredto: perform the random access procedure on the second BWP if the secondBWP meets the condition for performing a random access procedure.

26. The UE according to any one of Embodiments 23 to 25, where themeeting the condition for performing a random access procedure includesat least one of the following two: a resource used for random access isavailable; or a common search space CSS used to receive a random accessresponse RAR is available.

27. The UE according to any one of Embodiments 23 to 26, where that thecondition for performing a random access procedure is not met includesat least one of the following two: no resource used for random access isconfigured; or no common search space CSS used to receive a randomaccess response RAR is configured.

28. The UE according to any one of Embodiments 23 to 27, where whenperforming the RA procedure on the first BWP, the processor performs atleast any one of the following: skipping deactivating the first BWP;keeping the first BWP activated; stopping a bandwidth part inactivitytimer used to maintain the first BWP; continuing to use a value of apower ramping counter of the user equipment; continuing to use a backoffparameter of the user equipment; using a random access prioritycorresponding to the first BWP, and adjusting at least one of thefollowing based on at least the random access priority corresponding tothe first BWP: the backoff parameter, a power increment value, the powerramping counter, and a preamble counter preamble counter; continuing touse a first transmit beam, where the first beam is a transmit beam usedby the UE before or when the UE receives the switching indicationinformation; and switching from the first transmit beam to a secondtransmit beam, where the second transmit beam is different from thefirst transmit beam.

29. The UE according to any one of Embodiments 23 to 28, where thenetwork device configures a default BWP for the UE, the default BWPincludes a default downlink BWP, and the first BWP includes a firstdownlink BWP; and the first downlink BWP is different from the defaultdownlink BWP.

30. The UE according to any one of Embodiments 23 to 29, where whenperforming the RA procedure on the second BWP, the processor performs atleast any one of the following: setting the power ramping counter to aninitial value; setting the backoff parameter to an initial value, orsetting the backoff parameter to a value in a backoff indicator; using arandom access priority corresponding to the second BWP, and adjusting atleast one of the following based on at least the random access prioritycorresponding to the second BWP: the backoff parameter, the powerincrement value, the power ramping counter, and the preamble counterpreamble counter; continuing to use the first transmit beam, where thefirst beam is a transmit beam used by the UE before or when the UEreceives the switching indication information or before the UE switchesto the second BWP; and switching from the first transmit beam to thesecond transmit beam, where the second transmit beam is different fromthe first transmit beam.

31. The UE according to any one of Embodiments 23 to 29, where whenperforming the RA procedure on the second BWP, the processor performs atleast any one of the following: continuing to use the value of the powerramping counter of the user equipment; continuing to use the backoffparameter of the user equipment; using a random access prioritycorresponding to the second BWP, and adjusting at least one of thefollowing based on at least the random access priority corresponding tothe second BWP: the backoff parameter, the power increment value, thepower ramping counter, and the preamble counter preamble counter;continuing to use the first transmit beam, where the first beam is atransmit beam used by the UE before or when the UE receives theswitching indication information or before the UE switches to the secondBWP; and switching from the first transmit beam to the second transmitbeam, where the second transmit beam is different from the firsttransmit beam.

32. The UE according to any one of Embodiments 23 to 31, where whenperforming the RA procedure on the initial BWP, the processor performsat least any one of the following: setting the power ramping counter tothe initial value; setting the backoff parameter to the initial value,or setting the backoff parameter to the value in the backoff indicator;using a random access priority corresponding to the initial BWP, andadjusting at least one of the following based on at least the randomaccess priority corresponding to the initial BWP: the backoff parameter,the power increment value, the power ramping counter power rampingcounter, and the preamble counter preamble counter; continuing to usethe first transmit beam, where the first beam is a transmit beam used bythe UE before the UE switches to the initial BWP; and switching from thefirst transmit beam to the second transmit beam, where the secondtransmit beam is different from the first transmit beam.

33. The UE according to any one of Embodiments 23 to 32, where the firstBWP includes a first uplink UL BWP and/or a first downlink BWP, and thesecond BWP includes a second uplink UL BWP and/or a second downlink BWP;that the BWP switching indication information is used to instruct the UEto use the second BWP includes that the BWP switching indicationinformation is used to instruct the UE to use the second uplink UL BWP,or the second downlink BWP, or both the second uplink UL BWP and thesecond downlink BWP; and the BWP switching indication information isfurther used to instruct the UE to switch the first uplink UL BWP, orused to instruct the UE to switch the first downlink BWP, or used toinstruct the UE to switch the first uplink UL BWP and the first downlinkBWP.

34. A computer program product, including a computer program, where whenthe computer program is executed on a computer unit, the computer unitimplements the method according to any one of Embodiments 1 to 11.

The computer unit may be UE.

35. A computer program, where when the computer program is executed on acomputer unit, the computer unit implements the method according to anyone of Embodiments 1 to 11.

The computer unit may be UE.

36. A computer readable storage medium, storing a computer program,where when the computer program is executed on a computer, the computerimplements the method according to any one of Embodiments 1 to 11.

The computer may be UE.

37. An apparatus, including a processing module and a communicationsinterface, where the processing module is configured to perform themethod according to any one of Embodiments 1 to 11.

38. The apparatus according to Embodiment 37, where the apparatusfurther includes a storage module (which may be a memory), where thestorage module is configured to store an instruction, the processingmodule (which may be a processor) is configured to execute theinstruction stored in the storage, and execution of the instructionstored in the storage module enables the processing module to performthe method according to any one of Embodiments 1 to 11.

39. The apparatus according to Embodiment 37 or 38, where the apparatusis a chip or a chip system.

40. A system, including a network device and user equipment UE, wherethe UE works on a first bandwidth part BWP, where the first BWP is acurrently active BWP; when the UE needs to perform a random accessprocedure, the UE performs the random access procedure on an initial BWPif the first BWP does not meet a condition for performing a randomaccess procedure; or the UE performs the random access procedure on thefirst BWP if the first BWP meets a condition for performing a randomaccess procedure; when the UE performs the random access procedure onthe first BWP, the network device sends BWP switching indicationinformation to the UE, where the BWP switching indication information isused to instruct the UE to use a second BWP; and the UE continues toperform the random access procedure on the first BWP; or the UE stopsperforming the random access procedure on the first BWP, and the UEperforms the random access procedure on the second BWP.

The UE may be the UE according to any one of Embodiments 1 to 33.

41. A terminal, where the terminal is configured to perform the methodaccording to any one of Embodiments 1 to 11. The terminal may be UE.

There is no clear correspondence between numbers of the foregoingembodiments and numbers of the following embodiments, and the numbersare merely used for ease of description in this part.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic structural diagram of a bandwidth part and acarrier bandwidth according to this application;

FIG. 2 is a schematic diagram of a contention-based random accessprocedure in LTE;

FIG. 3 is a schematic diagram of a communications system to which thisapplication is applicable;

FIG. 4 is a schematic diagram of connection between a network device anduser equipment;

FIG. 5 is a schematic flowchart of a random access method according tothis application;

FIG. 6 is a schematic structural diagram of a random access apparatusaccording to this application; and

FIG. 7 is a schematic structural diagram of user equipment according tothis application.

DESCRIPTION OF EMBODIMENTS

The following clearly and completely describes the technical solutionsin the embodiments of this application with reference to theaccompanying drawings in the embodiments of this application.

Network elements in the embodiments of this application include anetwork device and user equipment. The network device is an accessdevice through which the user equipment accesses the mobilecommunications system in a wireless manner, and may be a NodeB (NodeB),an evolved NodeB (eNodeB), a base station in a 5G mobile communicationssystem, a next generation mobile communications NodeB (next generationNodeB, gNB), a base station in a future mobile communications system, anaccess node in a Wi-Fi system, or the like. The embodiments of thisapplication do not limit a specific technology used by the networkdevice or a specific device form.

The user equipment (user equipment, UE) may be alternatively referred toas a terminal, terminal equipment (Terminal equipment), a mobile station(mobile station, MS), a mobile terminal (mobile terminal, MT), or thelike. The user equipment may be a mobile phone (mobile phone), a tabletcomputer (pad), a computer with a wireless transceiving function,virtual reality (Virtual Reality, VR) user equipment, augmented reality(Augmented Reality, AR) user equipment, a wireless terminal inindustrial control (industrial control), a wireless terminal inself-driving (self-driving), a wireless terminal in a remote medicalsurgery (remote medical surgery), a wireless terminal in smart grid(smart grid), a wireless terminal in transportation safety(transportation safety), a wireless terminal in a smart city (smartcity), a wireless terminal in a smart home (smart home), or the like.

I. Bandwidth Part (Bandwidth Part, BWP)

In a new radio (New Radio, NR) system, the system supports a carrierwith a 400 MHz bandwidth. If all UEs need to support a carrier bandwidthof 400 MHz, not only a very high requirement is imposed on a bandwidthcapability of UE, but also higher energy consumption is caused to theUE. To reduce the requirement on the bandwidth capability of the UE, andreduce power consumption of the UE, a concept of a BWP is introduced tothe NR. The BWP supports UE in performing data transmission and arelated operation on a part of a bandwidth of a broad carrier.

As shown in FIG. 1, a bandwidth part includes N physical resource blocks(physical resource block, PRB), and each physical resource blockincludes K sub-carriers (sub-carrier), where N is an integer greaterthan or equal to 1 (for example, N=2), and K is an integer greater thanor equal to 1 (for example, K=12). The N physical resource blocks may becontinuous or discontinuous. A carrier bandwidth (carrier bandwidth) inFIG. 1 may be a frequency domain bandwidth provided by a carrier(carrier) working in a 4G or 5G mobile communications system, andincludes L PRBs, where L is an integer greater than or equal to 1, and Lis greater than or equal to N.

A network device may allocate at least one bandwidth part to userequipment served by the network device. Considering frequency-selectivefading (frequency-selective fading), bandwidth parts in differentlocations of a carrier bandwidth may have different fadingcharacteristics. For user equipment, a network device serving the userequipment may allocate, as far as possible, a bandwidth part having agood channel condition to the user equipment.

When a bandwidth of a cell is very high, a user may work on only a partof the bandwidth of the cell. Each bandwidth part of the cell isreferred to as a BWP, as shown in FIG. 2. Each BWP correspondinglysupports one physical layer parameter, which may be referred to asnumerology (Numerology). The numerology includes subcarrier spacingconfiguration and cyclic prefix length configuration. Different BWPs maysupport same numerology or different numerology.

A BWP may be understood as a frequency band having a different width.This application uses a BWP as an example name, and does not limitanother name, for example, a channel, a frequency channel, a frequencybandwidth, a frequency band, or frequency domain.

In this application, in a possible design, configuration information ofeach bandwidth part includes at least a physical resource block offset(PRB offset), the quantity of physical resource blocks (number of PRBs),and a sub-carrier spacing (subcarrier spacing).

The physical resource block offset may be an offset of a first physicalresource block included in a bandwidth part relative to a first physicalresource block included in an entire carrier bandwidth, as shown inFIG. 1. In addition, the configuration information of each bandwidthpart may further include at least one of the following parameters: acyclic prefix length (cyclic prefix length), a transmission timeinterval (transmission time interval, TTI), a center frequency (centerfrequency), and a frequency location (frequency location).

In addition, in another possible design, the configuration informationof each bandwidth part includes at least an index of the bandwidth part.The index of each bandwidth part may indicate the configurationinformation of the corresponding bandwidth part. Configurationinformation of a bandwidth part may include a plurality of parameters,for example, a physical resource block offset, the quantity of physicalresource blocks, and a subcarrier spacing. Further, configurationinformation of a bandwidth part corresponding to each index may furtherinclude at least one of the following parameters: a cyclic prefixlength, a transmission time interval, a center frequency, and afrequency location.

In this application, an initial bandwidth part (initial BWP) may be usedas a bandwidth part used in a process in which user equipmentestablishes a connection to a network device. The initial BWP isindicated by the network device in system information. Further, theinitial BWP is configured under a limitation of a capability of a UEdevice. A default bandwidth part (default BWP) may be used as abandwidth part used after the user equipment wakes up from a dormantprocess, or may be a bandwidth part used after the user equipment is outof uplink synchronization, or may be a bandwidth part used when the userequipment initiates random access. The default bandwidth part may be thesame as the initial bandwidth part.

The following conclusions have been reached in a progress of an existingNR standard:

In Rel-15, a serving cell of UE has a maximum of one active downlink(DownLink, DL) BWP and a maximum of one active uplink (UpLink, UL) BWP.

In an FDD (frequency division duplex, frequency division duplex)scenario, a DL BWP and a UL BWP in each serving cell of UE areseparately configured. In a TDD scenario, a DL BWP and a UL BWP in eachserving cell of UE are jointly configured as a bandwidth part pair (BWPpair); and the DL BWP and the UL BWP have a same center frequency, butmay have different bandwidths.

It should be noted that the BWP pair may be alternatively referred to asa BWP, and the BWP includes an uplink BWP and a downlink BWP. The BWPpair may be directly replaced with the BWP, and details are notdescribed in this application.

In the NR, the following two manners are supported during switching ofan active BWP (active BWP):

(1) Manner based on scheduling downlink control information (DownlinkControl Information, DCI): For the scheduling DCI manner, in the FDDscenario, DL-specific scheduling DCI is used to switch a DL active BWP,and UL-specific scheduling DCI is used to switch a UL active BWP; in theTDD scenario, one piece of scheduling DCI is used to switch from anactive BWP pair to another active BWP pair.

(2) Dedicated timer, for example, a bandwidth part inactivity timer (BWPinactivity timer): For the manner based on the dedicated timer, in theFDD scenario, if the timer expires, the UE switches from a currentlyactive DL BWP to a default DL BWP; in the TDD scenario, if the timerexpires, the UE switches from a currently active BWP pair to a defaultBWP pair.

In a primary cell (primary cell, PCell), for UE, in the NR, a commonsearch space (Common Search Space, CSS) used for an RA procedure may beconfigured in each BWP.

When performing an RA procedure on a BWP pair, the UE first needs tosend a preamble preamble on a UL BWP, and listens to RAR DCI in a CSS inthe DL BWP. The UE can perform the RA procedure on an active BWP paironly when a corresponding UL BWP has a PRACH resource, and acorresponding DL BWP has a CSS used for the RA procedure, that is, a CSSused to receive an RAR.

II. Random Access (Random Access) Procedure

In a conventional long term evolution (4th Generation, LTE) mobilecommunications system, that user equipment initially accesses a systemmainly includes three important steps: (1) an initial synchronizationand cell search process; (2) a network sends basic system information;and (3) a random access process. A detailed process is shown in FIG. 2.In step (1), the user equipment may obtain preliminary downlink timesynchronization and preliminary frequency synchronization based on aprimary synchronization signal (Primary Synchronization Signal, PSS) anda secondary synchronization signal (Secondary Synchronization Signal,SSS), obtain symbol synchronization and frame synchronization, andobtain information such as a cyclic prefix and a cell ID. In step (2), asystem sends a basic system message, namely, a system information block(system information block, SIB) message, and the user equipment receivesthe basic system message (the SIB message), reads the basic systeminformation, to obtain a network configuration message of uplink randomaccess, and provides related information for the random access procedurein the third step. In step (3), the user equipment obtains resourceconfiguration information of uplink random access based on the basicsystem information provided by the system, and performs an uplink randomaccess procedure. According to a conclusion reached in the 3GPPstandard, in the uplink random access procedure, a contention-basedrandom access procedure still uses a method similar to sending fourmessages in a conventional LTE system. To be specific, the userequipment sends a preamble (preamble), the network device feeds back arandom access response (Random Access Response, RAR), the user equipmentsends a message-3 message, and the network device replies with amessage-4 message to perform contention resolution, so as to complete afinal uplink random access procedure.

An existing contention-based random access manner is shown in FIG. 2.First, UE sends a random access preamble (random access preamble) to aneNB, notifies the eNodeB (eNB for short) of a random access request, andenables the eNB to estimate a transmission delay between the eNB and theUE and calibrate uplink timing (timing advance, TA) according to thetransmission delay. After sending the preamble, the UE listens on aPDCCH within a time window of a random access feedback, to receive anRAR message replied with by the eNB. Because a resource of the preamblemay be used by a plurality of UEs, to distinguish between different UEs,subsequently, each UE sends a third message in an RA procedure, wherethe information includes a unique identity of the UE. In other words,the UEs have different unique identities. In the final step, the eNBreplies with a unique identity of UE in the third message in the RAprocedure, to notify which UE or UEs succeeds or succeed in channelcontention.

III. Mapping Between a Logical Channel and Numerology/Transmission TimeLength in an NR System

In the NR system, user equipment may have a plurality of services at thesame time. Services having a same QoS requirement may be mapped to asame data radio bearer for transmission. Services having different QoSrequirements need to be mapped to different data radio bearers fortransmission.

During transmission, each of the services having different QoSrequirements needs to be transmitted by using an uplink grant (UL grant)that corresponds to numerology (specifically including a subcarrierspacing (subcarrier spacing) and a cyclic prefix (cyclic prefix) length)and a transmission time length that can support a corresponding QoSrequirement.

To ensure that a data packet on a data radio bearer can be transmittedby using a UL grant of numerology and a transmission time length thatmatch a QoS requirement of the data packet, a base station configures amapping relationship between a logical channel corresponding to a dataradio bearer and numerology/transmission time length for the userequipment. After the UE receives a UL grant allocated by the basestation, if numerology/transmission time length that is used for datatransmission and that is indicated in the UL grant matches a logicalchannel, the user equipment can transmit data of the logical channel byusing the UL grant. Otherwise, the data of the logical channel cannot betransmitted by using the UL grant.

User equipment may support data transmission on one carrier by using ULgrants of a plurality of numerology/transmission time lengths, or maysupport, if carrier aggregation is configured, data transmission ondifferent carriers by using UL grants of a plurality ofnumerology/transmission time lengths.

One logical channel of user equipment may be configured to be associatedwith one or more SRs (Scheduling Request, scheduling request).

The base station may learn, based on SR configuration corresponding toan SR signal sent by the UE and an association relationship between SRconfiguration and a logical channel, a UL grant that corresponds to aspecific numerology/transmission time length combination and that isrequired by the UE to transmit data.

To meet a requirement of a wireless data communication traffic thatincreases due to deployment of the 4G communications system, 3GPP hasstarted to improve or extend the 4G communications system. Therefore, a5G or pre-5G communications system is also referred to as a “super 4Gnetwork”, a “post LTE (Long Term Evolution, long term evolution)system”, or an NR. In the 3GPP, the 5G communications system isconsidered to be implemented at approximately 4 GHz such as 3300 MHz to4990 MHz, at approximately 30 GHz such as 24.25 GHz to 52.6 GHz, and atapproximately 70 GHz such as 66 GHz to 86 GHz. Working frequency bandsof approximately 30 GHz and approximately 70 GHz are collectivelyreferred to as a high frequency (High frequency, HF), and a higher datarate can be implemented. To reduce a radio propagation loss and increasea transmission distance, antenna technologies such as beamforming,massive multiple input multiple output (MIMO), full-dimension MIMO(FD-MIMO, Full-Dimension MIMO), an array antenna, digital beamforming(Digital Beamforming), and analog beamforming (Analog Beamforming) havebeen discussed in the 5G communications system.

A network device such as a gNB, a TRxP (also referred to as a TRP), or acell in the 5G communications system may interact with user equipmentsuch as UE by using a beamforming (Beamforming) technology. The networkdevice may usually form a plurality of downlink transmit beams ((downlink DL) Tx Beam), where the Tx beam is a transmit beam, a transmissionbeam, or a transmitting beam, and send a downlink signal to UE incoverage of one or more DL Tx beams on the DL Tx beam or the DL Txbeams. The UE may perform receiving by using a receive beam Rx beam oran omnidirectional antenna, where the Rx beam is a receive beam or areceiving beam, to obtain a higher array gain. A higher datatransmission rate is implemented between the network device and the userequipment by using the beamforming technology.

This application may be applied to a wireless communications systemshown in FIG. 3, including a scenario such as an NR scenario, an LTEnext generation scenario, a WLAN scenario, or a Bluetooth communicationscenario. For ease of description, the embodiments of this applicationare described by using the NR scenario as an example. As shown in FIG.3, the NR scenario may include a new radio core network such as (NewRadio new radio access technology core, NR_newRAT-Core), and a new radioaccess network. Function entities in the NR scenario mainly include anetwork device and user equipment that is connected to the networkdevice in the new radio access network, for example, user equipment 1 inFIG. 3, and may further include a relay device and user equipment thatis connected to a relay, for example, user equipment 2 in FIG. 3. Therelay device is connected to the network device by using a link 2, andtherefore, for the network device, the relay device may be alternativelyconsidered as user equipment. The relay device is connected to the userequipment 2 by using a link 3, and therefore, for the user equipment,the relay device may be alternatively considered as a network device.Therefore, it should be understood that the network device in thisapplication may further include a relay device, and the user equipmentin this application may further include a relay device. The networkdevice may be specifically any one of or a combination of several of agNB, a new radio eNodeB (New radio eNB), a transmission and receptionpoint (transmission and reception point, TRP), a macro base station, amicro base station, a high frequency base station, an LTE macro or microeNB, CPE, a WLAN AP, a WLAN group owner (group owner, GO), and the like.For example, the network device may be a gNB, and the gNB implementsfunctions of the network device in the present invention, or the networkdevice is a combination of a gNB and a TRP, for example, the gNBimplements a resource configuration function of the network device inthis application, and the TRP implements sending and receiving functionsof the network device in the present invention. This application is notlimited thereto. The user equipment may be a mobile phone, a tabletcomputer, an intelligent vehicle, a sensing device, an IOT device,wireless customer-premises equipment (Customer-Premises Equipment, CPE),a relay base station, or the like.

As shown in FIG. 4, a network device may form a plurality of transmitbeams or receive beams by using the beamforming technology, for example,digital beamforming (Digital Beamforming) or analog beamforming (AnalogBeamforming). The beams may have a same coverage angle or differentcoverage angles, and beams having different coverage angles may overlap.For example, the network device may send control information by using abeam having a relatively wide coverage angle, and send data informationby using a beam having a relatively narrow coverage angle. The userequipment may receive, within coverage of one or more beams, a beamcluster, or a beam group, information sent by the network device.

The user equipment may also form a plurality of receive beams by usingthe beamforming technology, and determine to use one or more receivebeams to perform receiving in correspondence to a downlink beam used bythe network device. For ease of description, a beam in the embodimentsof the present invention may be a single beam or a plurality of beams.

Therefore, a downlink transmit beam of the network device and acorresponding receive beam of the user equipment, or an uplink transmitbeam of the user equipment and a corresponding receive beam of thenetwork device may be referred to as a beam pair beam pair. Atransmission link formed by the beam pair is referred to as a beam pairlink (Beam Pair Link, BPL). For example, when the network device in FIG.4 uses a beam 3 as a downlink transmit beam, the user equipment maydetermine to use a beam 6 as a corresponding receive beam, and the beam3 and the beam 6 form a BPL. When a beam of the network device or theuser equipment meets a beam correspondence (Beam Correspondence)feature, a corresponding receive beam or transmit beam may be determinedbased on a transmit beam or a receive beam.

In this application, a beam may be alternatively referred to as a beam,a beam may be directly replaced with a beam, or a beam may be directlyreplaced with a beam. Details are not described in this application.

Optionally, a beam may be alternatively referred to as a direction, anda beam may be directly replaced with a direction, or a direction may bedirectly replaced with a beam. For example, a first beam may be replacedwith a first direction, or a first direction may be replaced with afirst beam. Details are not described in this application.

Optionally, a beam may be alternatively referred to as a spatialresource, and a beam may be directly replaced with a spatial resource,or a spatial resource may be directly replaced with a beam. Details arenot described in this application.

Optionally, a beam may be alternatively referred to as a precodingvector, and a beam may be directly replaced with a precoding vector, ora precoding vector may be directly replaced with a beam. Details are notdescribed in this application.

A network device may be alternatively referred to as a gNB, and anetwork device may be directly replaced with a gNB, or a gNB may bedirectly replaced with a network device. Details are not described inthis application.

Optionally, a network device may be alternatively referred to as a TRP,and a network device may be directly replaced with a TRP, or a TRP maybe directly replaced with a network device. Details are not described inthis application.

Optionally, identity information of a beam may be alternatively referredto as index information of the beam, and the identity information of thebeam may be directly replaced with the index information of the beam, orthe index information of the beam may be directly replaced with theidentity information of the beam. Details are not described in thisapplication.

The identity information of the beam may be alternatively referred to asbeam identity information, and the identity information of the beam maybe directly replaced with the beam identity information, or the beamidentity information may be directly replaced with the identityinformation of the beam. Details are not described in this application.

Optionally, a beam/beam may be understood as a spatial resource, and maybe a sending or receiving precoding vector having energy transmissiondirectivity/direction. In addition, the sending or receiving precodingvector can be identified by using index information. The energytransmission directivity may mean that a signal precoded by using theprecoding vector has a relatively good receiving power when the signalis received in a particular spatial location, for example, a receivingdemodulation signal to noise ratio is met. The energy transmissiondirectivity may alternatively mean that a plurality of same signals sentin different spatial locations has different receiving powers when thesignals are received by using the precoding vector. That a device usesdifferent beams may be understood as that the device uses differentspatial resources. Optionally, an uplink spatial resource and/or adownlink spatial resource, or a spatial resource used to sendinformation and a spatial resource used to receive information arefurther distinguished.

Optionally, a beam may be understood as a main lobe formed by using asending mode of an antenna array, for example, the beam (of the antenna)is the main lobe of the radiation pattern of an antenna array.

Optionally, one communications device (for example, a terminal device ora network device) may have different precoding vectors. Differentdevices may also have different precoding vectors, that is, correspondto different beams. Different beams may correspond to differentdirections. That a device uses different beams may be understood as thata device uses different precoding vectors. Optionally, an uplinkprecoding vector and a downlink precoding vector, or a precoding vectorused to send information and a precoding vector used to receiveinformation are further distinguished.

Optionally, a beam/beam may be further understood as a spatial domaintransmission filter (spatial domain transmission filter). That a device(for example, a network device and/or user equipment) uses a beam may bereplaced with that a device uses a spatial domain transmission filter.

Optionally, for configuration or a capability of a communicationsdevice, the communications device may use one or more of a plurality ofdifferent precoding vectors at a same moment, that is, may form one ormore beams at the same time. Information about the beam may beidentified by using index information. Optionally, the index informationmay correspond to an identity (identity, ID) of a resource configuredfor the UE. For example, the index information may correspond to an IDor a resource of a configured channel state information reference signal(Channel status information Reference Signal, CSI-RS), or may correspondto an ID or a resource of a configured uplink sounding reference signal(Sounding Reference Signal, SRS). Alternatively, optionally, the indexinformation may be a signal carried by using a beam or index informationexplicitly or implicitly carried on a channel. For example, the indexinformation may be a synchronization signal sent by using a beam or theindex information of the beam may be indicated by using a broadcastchannel.

A beam pair may include a transmit beam of a transmit end and a receivebeam of a receive end, alternatively referred to as an uplink beam or adownlink beam. For example, a beam pair may include a gNB Tx beamtransmit beam or a UE Rx beam receive beam, or a UE Tx beam transmitbeam or a gNB Rx beam receive beam. The transmit beam may bealternatively understood as a transmit beam.

Optionally, the identity information of the beam may be specifically oneor more of an ID of the beam, an ID generated based on the ID of thebeam, a name of the beam, an index of the beam, an index generated basedon the index of the beam, a derivative value of the ID of the beam, aderivative value of the name of the beam, a derivative value of theindex of the beam, a hash value of the ID of the beam, a hash value ofthe name of the beam, a hash value of the index of the beam, a truncatedvalue of the ID of the beam, a truncated value of the name of the beam,a truncated value of the index of the beam, a hash value of the ID ofthe beam plus plaintext information, a hash value of the name of thebeam plus plaintext information, a hash value of the index of the beamplus plaintext information, a map of the ID of the beam, a map of thename of the beam, a map of the index of the beam, and a map of the beam.

A beam (for example, an N^(th) beam, where N is any beam supported by adevice) used by the device is not limited. For ease of understanding, anexample in which the device uses a first beam is used.

Optionally, for example, that the device uses the first beam may bereplaced with that the device is in a first direction. Further, that thedevice uses a first transmit beam may be replaced with that the deviceis in a first sending direction, and/or that the device uses a firstreceive beam may be replaced with that the device is in a firstreceiving direction.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstspatial resource. Further, that the device uses a first transmit beammay be replaced with that the device uses a first sending spatialresource, and/or that the device uses a first receive beam may bereplaced with that the device uses a first receiving spatial resource.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstantenna mode. Further, that the device uses a first transmit beam may bereplaced with that the device uses a first sending antenna mode, and/orthat the device uses a first receive beam may be replaced with that thedevice uses a first receiving antenna mode.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstantenna mode. Further, that the device uses a first transmit beam may bereplaced with that the device uses a first sending antenna mode, and/orthat the device uses a first receive beam may be replaced with that thedevice uses a first receiving antenna mode.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstantenna array mode. Further, that the device uses a first transmit beammay be replaced with that the device uses a first transmit antenna arraymode, and/or that the device uses a first receive beam may be replacedwith that the device uses a first receive antenna array mode.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstspatial domain transmission filter.

Further, that the device uses a first transmit beam may be replaced withthat the device uses a first spatial domain transmission filter used forsending, and/or that the device uses a first receive beam may bereplaced with that the device uses a first spatial domain transmissionfilter used for receiving.

Optionally, for example, that the device uses a first transmit beam (oris in a first direction) may be replaced with that the device uses afirst sending spatial domain transmission filter, and/or that the deviceuses a first receive beam may be replaced with that the device uses afirst receiving spatial domain transmission filter.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstprecoding vector. Further, that the device uses a first transmit beammay be replaced with that the device uses a first sending precodingvector, and/or that the device uses a first receive beam may be replacedwith that the device uses a first receiving precoding vector.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstweight. Further, that the device uses a first transmit beam may bereplaced with that the device uses a first sending weight, and/or thatthe device uses a first receive beam may be replaced with that thedevice uses a first receiving weight.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstparameter (for example, a parameter in an antenna array). Further, thatthe device uses a first transmit beam may be replaced with that thedevice uses a first sending parameter, and/or that the device uses afirst receive beam may be replaced with that the device uses a firstreceiving parameter.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses a firstweighting parameter (for example, different antennas in an antenna arrayuse different parameters). Further, that the device uses a firsttransmit beam may be replaced with that the device uses a first sendingweighting parameter, and/or that the device uses a first receive beammay be replaced with that the device uses a first receiving weightingparameter.

Optionally, for example, that the device uses a first beam (or is in afirst direction) may be replaced with that the device uses firstbeamforming. Further, that the device uses a first transmit beam may bereplaced with that the device uses first transmit beamforming, and/orthat the device uses a first receive beam may be replaced with that thedevice uses first receive beamforming.

Optionally, a transmit beam (or referred to as a downlink beam) used bythe network device corresponds to a channel state information referencesignal resource indicator (CSI-RS Channel State Information ReferenceSignal resource indicator, CRI). For example, a first transmit beam (ora first direction) corresponds to a first CRI, and a second transmitbeam (or a second direction) corresponds to a second CRI. Optionally,that the network device sends information on a first channel stateinformation reference signal resource means that the network device usesthe first transmit beam. Optionally, that the user equipment indicates aCRI of the network device means that the UE indicates a transmit beam ofthe network device. For example, optionally, that the UE indicates thefirst CRI of the network device means that the UE indicates the firsttransmit beam of the network device.

Optionally, a transmit beam (or referred to as a downlink beam) used bythe network device corresponds to a synchronization signal blockresource indicator (SSB synchronization signals block resourceindicator, SBRI). For example, a first transmit beam (or a firstdirection) corresponds to a first SBRI, and a second transmit beam (or asecond direction) corresponds to a second SBCRI. Optionally, that thenetwork device sends information on a first synchronization signal blockresource means that the network device uses the first transmit beam.Optionally, that the UE indicates an SBRI of the network device meansthat the UE indicates a transmit beam of the network device. Forexample, optionally, that the UE indicates the first SBRI of the networkdevice means that the UE indicates the first transmit beam of thenetwork device.

Optionally, a transmit beam (or referred to as a downlink beam) used bythe network device corresponds to a synchronization signal block(synchronization signals block index, SSB) index (index). For example, afirst transmit beam (or a first direction) corresponds to a first SSBindex, and a second transmit beam (or a second direction) corresponds toa second SSB index.

Optionally, that the network device sends information on a resourcecorresponding to a first SSB means that the network device uses a firsttransmit beam. Optionally, that the UE indicates an SSB index of thenetwork device means that the UE indicates a transmit beam of thenetwork device. For example, optionally, that the UE indicates the firstSSB index of the network device means that the UE indicates the firsttransmit beam of the network device.

Optionally, a transmit beam (or referred to as a downlink beam) used bythe network device corresponds to an SSB time index (SSB,synchronization signals block time index, synchronization signal blocktime index). For example, a first transmit beam (or a first direction)corresponds to a first SSB time index, and a second transmit beam (or asecond direction) corresponds to a second SSB time index. Optionally,that the network device sends information on a resource corresponding toa first SSB time means that the network device uses the first transmitbeam. Optionally, the UE indicates an SSB time index of the networkdevice means that the UE indicates a transmit beam of the networkdevice. For example, optionally, that the UE indicates the first SSBtime index of the network device means that the UE indicates the firsttransmit beam of the network device.

In this application, that the user equipment sends information to thenetwork device may be alternatively referred to as that the userequipment sends information to the network device, and that the userequipment sends information to the network device may be replaced withthat the user equipment sends information to the network device. This isnot limited in this application.

How UE uses a BWP when the UE needs to perform a random access procedureis a problem that needs to be resolved in this application.

In this application, a BWP switching process may be a process ofswitching, by the UE, from a source BWP (which may be referred to as afirst BWP) to another target BWP (which may be referred to as a secondBWP or an initial BWP). This switching is switching between BWPs. To bespecific, the source BWP and the target BWP may be controlled by a samenetwork device, or may be controlled by different network devices.

The following describes the embodiments of this application withreference to the accompanying drawings.

As shown in FIG. 5, this application provides a random access method.The method includes the following steps.

Step 50: UE works on a first BWP, where the first BWP is a currentlyactive BWP.

Step 51: The UE needs to perform a random access procedure.

A case in which the UE needs to perform the random access procedureoptionally includes at least one of the following cases: A networkdevice instructs the UE to perform RA, or the UE needs to perform therandom access procedure when a counter (counter) corresponding toscheduling request configuration (SR configuration) of the UE reaches alargest value, or the UE is out of synchronization, or radio linkinterruption (radio link failure) occurs in the UE, or the UE needs toestablish a radio resource control (RRC) connection to a gNB.

Step 52: Determine whether the first BWP meets a condition forperforming a random access procedure.

Step 53: The UE performs the random access procedure on an initial BWPif the first BWP does not meet the condition for performing a randomaccess procedure.

The performing, by the UE, the random access procedure on an initial BWPincludes: performing, by the UE, the random access procedure on theinitial BWP when the initial BWP meets the condition for performing arandom access procedure.

Specifically, the performing, by the UE, the RA procedure on an initialBWP includes at least any one of the following: setting, by the UE, apower ramping counter to an initial value; setting, by the UE, thebackoff parameter to an initial value, or setting the backoff parameterto a value indicated in a backoff indicator; using, by the UE, an RApriority corresponding to the initial BWP, and adjusting, based on atleast the RA priority corresponding to the initial BWP, at least one ofthe backoff parameter, a power increment value, the power rampingcounter (power ramping counter), and a preamble counter preamble counter(preamble counter) preamble counter; continuing, by the UE, to use afirst transmit beam, where the first beam is a transmit beam used by theUE before the UE switches to the initial BWP; and switching, by the UE,from the first transmit beam to a second transmit beam, where the secondtransmit beam is different from the first transmit beam.

According to the method provided in this application, the UE switches tothe initial BWP when the initial BWP meets the condition for performinga random access procedure, to quickly implement the random accessprocedure.

Step 54: The UE performs the random access procedure on the first BWP ifthe first BWP meets the condition for performing a random accessprocedure.

The performing, by the UE, the random access procedure on the first BWPincludes at least any one of the following: skipping, by the UE,deactivating the first BWP; keeping, by the UE, the first BWP activated;stopping, by the UE, a bandwidth part inactivity timer used to maintainthe first BWP; continuing to use a value of the power ramping counter ofthe user equipment; continuing to use the backoff parameter of the userequipment; using, by the UE, a random access priority corresponding tothe first BWP, and adjusting, based on the random access prioritycorresponding to the first BWP, at least one of the backoff parameter,the power increment value, the power ramping counter (power rampingcounter), and the preamble counter preamble counter (preamble counter)preamble counter; continuing, by the UE, to use the first transmit beam,where the first beam is a transmit beam used by the UE before or whenthe UE receives switching indication information; and switching, by theUE, from the first transmit beam to the second transmit beam, where thesecond transmit beam is different from the first transmit beam.

According to the method, a parameter setting of the UE is specified whenthe UE performs a random procedure on the first BWP. Specifically, thebandwidth part inactivity timer used to maintain the first BWP isstopped, to prevent uncertainty of whether the UE switches a BWP due totriggering of the bandwidth part inactivity timer in the random accessprocedure, and better implement interworking. The first BWP maintains inan active state, to ensure consistency with a state machine of the UE,and prevent a case in which UE in different states performs differentactions. The parameters, for example, the value of the power rampingcounter and the backoff parameter, used by the UE when the random accessprocedure continues to be performed on the first BWP continue to beused, so that inappropriate impact caused to a system by a change of theparameter of the UE can be prevented, interference caused to a networkcan be avoided, and unfair contention can be avoided. The UE continuesto use the first transmit beam, so that the random access procedure ofthe UE can be accelerated, and the UE implements standardization of therandom access procedure, to reduce impact caused by the UE to thenetwork.

Step 55: When the UE performs the random access procedure on the firstBWP, the UE receives BWP switching indication information sent by anetwork device, where the BWP switching indication information is usedto instruct the UE to use a second BWP.

After step 55, the UE may choose to perform one of step 56 and step 57.

It should be noted that in this application, the first BWP includes afirst uplink BWP and/or a first downlink BWP, and the second BWPincludes a second uplink BWP and/or a second downlink BWP.

That the BWP switching indication information is used to instruct the UEto use the second BWP includes that the BWP switching indicationinformation is used to instruct the UE to use the second uplink BWP, orthe BWP switching indication information is used to instruct the UE touse the second downlink BWP, or the BWP switching indication informationis used to instruct the UE to use the second uplink BWP and the seconddownlink BWP. The BWP switching indication information is further usedto instruct the UE to switch the first uplink BWP, or the BWP switchingindication information is further used to instruct the UE to switch thefirst downlink BWP, or the BWP switching indication information isfurther used to instruct the UE to switch the first uplink BWP and thefirst downlink BWP.

Step 56: The UE continues to perform the random access procedure on thefirst BWP.

Step 57: The UE stops performing the random access procedure on thefirst BWP, and the UE performs the random access procedure on the secondBWP.

The UE performs the random access procedure on the second BWP when thesecond BWP meets the condition for performing a random access procedure.

In this application, meeting the condition for performing a randomaccess procedure includes at least one of the following two: A resourceused for random access is available, or a CSS used to receive a randomaccess response RAR is available.

According to the method, if a resource used for random access isavailable in a BWP, it may be determined that the BWP meets thecondition for performing a random access procedure, so that the UE sendsuplink information on the determined BWP. If a CSS used to receive anRAR is available in a BWP, it may be determined that the BWP meets thecondition for performing a random access procedure, so that the UEreceives downlink information on the determined BWP. Therefore, the UEquickly implements the random access procedure.

That the condition for performing a random access procedure is not metincludes at least one of the following two: no resource used for randomaccess is configured, or no CSS used to receive a random access responseRAR is configured.

According to the method, if the resource used for random access is notavailable in a BWP, the UE quickly determines that the random accessprocedure cannot be initiated on the BWP, or if the CSS used to receivean RAR is not available in a BWP, the UE quickly determines thatdownlink information cannot be received on the BWP, so that the UEselects a BWP meeting the condition for performing a random accessprocedure, to implement the random access procedure.

Further, the network device configures a default BWP for the UE. Thedefault BWP includes a default downlink BWP. The first BWP includes thefirst downlink BWP. The first downlink BWP is different from the defaultdownlink BWP.

The first BWP is different from the default BWP, to distinguish anobject specific to the bandwidth part inactivity timer, and prevent thebandwidth part inactivity timer from being blindly started and/orstopped.

-   -   In step 57, in a possible design, the performing, by the UE, the        RA procedure on the second BWP includes at least any one of the        following: setting, by the UE, the power ramping counter to the        initial value; setting, by the UE, the backoff parameter to the        initial value, or setting the backoff parameter to the value        indicated in the backoff indicator; using, by the UE, an RA        priority corresponding to the second BWP, and adjusting, based        on at least the RA priority corresponding to the second BWP, at        least one of the backoff parameter, the power increment value,        the power ramping counter (power ramping counter), and the        preamble counter preamble counter (preamble counter) preamble        counter; continuing, by the UE, to use the first transmit beam,        where the first beam is a transmit beam used by the UE before or        when the UE receives the switching indication information or        before the UE switches to the second BWP; and switching, by the        UE, from the first transmit beam to the second transmit beam,        where the second transmit beam is different from the first        transmit beam.

According to the method, when performing the RA procedure on the secondBWP, the UE initializes some used parameters, for example, initializesthe value of the power ramping counter and the backoff parameter. Inthis way, the UE may not need to keep the parameters, andincompatibility with the original random access procedure is avoided, sothat the UE implements standardization of the random access procedure,to reduce impact caused by the UE to the network.

In step 57, in another possible design, the performing, by the UE, theRA procedure on the second BWP includes at least any one of thefollowing: continuing to use the value of the power ramping counter ofthe user equipment; continuing to use the backoff parameter of the userequipment; using, by the UE, a random access priority corresponding tothe second BWP, and adjusting, based on at least the random accesspriority corresponding to the second BWP, at least one of the backoffparameter, the power increment value, the power ramping counter (powerramping counter), and the preamble counter preamble counter (preamblecounter) preamble counter; continuing, by the UE, to use the firsttransmit beam, where the first beam is a transmit beam used by the UEbefore or when the UE receives switching indication information orbefore the UE switches to the second BWP; and switching, by the UE, fromthe first transmit beam to the second transmit beam, where the secondtransmit beam is different from the first transmit beam.

According to the method provided in this application, when the UEperforms the RA procedure on the second BWP, the UE continues to usesome original parameters, for example, continues to use the value of thepower ramping counter and the backoff parameter, so that inappropriateimpact caused to the system by a change of the parameter used by the UEcan be prevented, interference caused to the network can be avoided, andunfair contention can be avoided. The UE continues to use the firsttransmit beam, so that the random access procedure of the UE can beaccelerated. The UE switches to the second transmit beam, so that the UEcan obtain a better reception gain, and the UE implementsstandardization of the random access procedure, to reduce impact causedby the UE to the network.

In a possible design, if both the first BWP and the second BWP meet thecondition for performing a random access procedure, selecting one BWPfrom the first BWP and the second BWP based on a preset selectioncondition, to perform the random access procedure includes:

(1) The UE selects a BWP having relatively high numerology (numerology)from the first BWP and the second BWP, to perform the random accessprocedure.

(2) The UE selects a BWP having a relatively high random accessconfiguration priority from the first BWP and the second BWP, to performthe random access procedure.

(3) The UE selects, from the first BWP and the second BWP, a BWP havinga non-contention-based random access resource, to perform the randomaccess procedure.

(4) If the counter corresponding to the scheduling request configurationof the UE reaches a largest value, the UE selects a BWP corresponding toan LCH logical channel corresponding to the scheduling requestconfiguration, to perform the random access procedure.

(5) The UE selects a BWP whose corresponding LCH logical channel hasbuffer data, to perform the random access procedure.

(6) If an LCH logical channel corresponding to the first BWP has bufferdata, and an LCH logical channel corresponding to the second BWP hasbuffer data, the UE selects a BWP whose corresponding LCH logicalchannel has a higher priority or a BWP whose corresponding LCH logicalchannel has a higher random access configuration priority, to performthe random access procedure.

(7) If the first transmit beam of the UE cannot reach the network deviceon the second BWP, the UE selects the first BWP to perform the randomaccess procedure, where the first transmit beam is a transmit beam usedby the UE on the first BWP.

(8) If the second transmit beam of the UE cannot reach the networkdevice on the first BWP, the UE selects the second BWP to perform therandom access procedure, where the second transmit beam is a transmitbeam used by the UE on the second BWP.

(9) If the UE switches from the first transmit beam to the secondtransmit beam, and the second transmit beam of the UE cannot reach thenetwork device on the second BWP, the UE selects the first BWP, toperform the random access procedure.

(10) If the UE switches from the first transmit beam to the secondtransmit beam, and the second transmit beam of the UE cannot reach thenetwork device on the first BWP, the UE selects the second BWP, toperform the random access procedure.

According to the method, the UE currently works on the first BWP, andcan select, based on whether the first BWP meets the condition forperforming a random access procedure, which BWP is used to perform therandom access procedure. Further, the UE receives the BWP switchingindication information when performing the random access procedure onthe first BWP, to choose whether to continue to complete the randomaccess procedure on the first BWP, or switch to the second BWP tocomplete the random access procedure, to ensure that the UE completesrandom access in a timely manner.

The following describes in detail the foregoing random access method byusing several examples.

Example 1

The UE performs an RA procedure on a currently active first BWP pair,and receives a BWP switching instruction, and the UE cannot perform theRA procedure on a second BWP pair that is activated after BWP switchingis performed, where the second BWP pair includes a second UL BWP and asecond DL BWP. This may be specifically any one of the following cases:

(1) The UE receives UL BWP switching indication information, and nophysical random access channel resource resource (Physical Random AccessChannel, PRACH) used for random access is configured in the second ULBWP.

(2) The UE receives DL BWP switching indication information, and no CSSused to receive an RAR is configured in the second DL BWP.

(3) The UE receives BWP pair switching indication information, and noPRACH resource used for random access is configured in the second UL BWPand/or no CSS used to receive an RAR is configured in the second DL BWP.

If any one of the foregoing three cases occurs, the UE continues toperform the RA procedure on the currently active first BWP pair, and theUE performs a BWP switching process after completing the RA procedure.

It should be noted that a BWP pair may be alternatively referred to as aBWP, and the BWP includes an uplink BWP and a downlink BWP.

In this way, the UE can complete the random access procedure in a timelymanner, to avoid a case in which the random access procedure cannot becompleted after the second BWP pair is switched to.

Example 2

The UE performs an RA procedure on a currently active first BWP pair,and receives BWP switching indication information, and the UE mayperform the RA procedure on a second BWP pair. This may be specificallyany one of the following cases:

(1) The UE receives UL BWP switching indication information, and a PRACHresource used for random access is configured in a second UL BWP, wherea BWP pair that is activated after BWP switching is performed includesthe second UL BWP and a first DL BWP.

(2) The UE receives DL BWP switching indication information, and a CSSused to receive an RAR is configured in a second DL BWP, where a BWPpair that is activated after BWP switching is performed includes thesecond DL BWP and a first UL BWP.

(3) The UE receives BWP pair switching indication information, a PRACHresource used for random access is configured in a second UL BWP, and aCSS used to receive an RAR is configured in a second DL BWP.

If any one of the foregoing three cases occurs, in a possible design,the UE continues the RA procedure on the currently active first BWPpair, and the UE executes a BWP switching instruction after completingthe RA procedure.

In another possible design, the UE stops the RA procedure on thecurrently active first BWP pair, and the UE performs a BWP switchingprocess, reinitiates the RA procedure on a second BWP pair that isactivated after the switching, and initializes random access parameterssuch as a counter and a backoff parameter.

In another possible design, the UE stops the RA procedure on thecurrently active first BWP pair, the UE performs a BWP switching processand continues the RA procedure on a second BWP pair that is activatedafter the switching, and the UE continues to use random accessparameters such as a counter and a backoff parameter, and does notinitialize the parameters.

In another possible design, the UE completes a current round of RAprocedure on the currently active first BWP pair; and if the RAprocedure fails, the UE performs a BWP switching process, reinitiate theRA procedure on a second BWP pair that is activated after the switching,and initializes random access parameters such as a counter and a backoffparameter; or if the RA procedure succeeds, the UE merely needs toperform a BWP switching process, and in this case, does not need toreinitiate the RA procedure on a second BWP pair that is activated afterthe switching.

In another possible design, the UE completes a current round of RAprocedure on the currently active first BWP pair; and if the RAprocedure fails, the UE performs a BWP switching process and reinitiatesthe RA procedure on a second BWP pair that is activated after theswitching, and the UE continues to use random access parameters such asa counter and a backoff parameter, and does not initialize theparameters; or if the RA procedure succeeds, the UE merely needs toperform a BWP switching process.

It should be noted that a BWP pair may be alternatively referred to as aBWP, and the BWP includes an uplink BWP and a downlink BWP.

According to the foregoing process, the UE can switch to the second BWPto complete the random access procedure, and set a parameter used in therandom access procedure, to meet a requirement of a standard setting,reduce interference to a network, and implement interworking.

Example 3

The UE needs to perform RA. For the currently active first BWP pair,which is also referred to as the first BWP, if no PRACH resource usedfor random access is configured in a first UL BWP and/or no CSS used toreceive an RAR is configured in a first DL BWP, the UE switches to adefault BWP pair, which is also referred to as a default BWP, toinitiate an RA procedure.

Alternatively, when the UE needs to perform contention-based RACH, ifthe currently active first BWP pair of the UE is not a default BWP pair,the UE switches to the default BWP pair to initiate an RACH procedure.

After the RA procedure is completed, an active BWP pair of the UE is thedefault BWP pair.

Optionally, after the RA procedure is completed, the UE may switch tothe original first BWP pair.

The default BWP pair may be an initial active BWP pair, or the defaultBWP pair is a BWP in which a PRACH resource is configured, or thedefault BWP pair is a BWP configured by the network device for the UE.

It should be noted that a BWP pair may be alternatively referred to as aBWP, and the BWP includes an uplink BWP and a downlink BWP.

In this way, the UE may switch to a BWP pair in which an RACH resourceused for random access is configured, to complete the RA procedure, sothat the UE can complete the RA procedure in a timely manner. Then, theUE activates the default BWP pair. Alternatively, the UE switches to theoriginal active (active) first BWP pair after completing the RAprocedure.

Example 4

The network device configures at least a first BWP and a second BWP forthe UE, and the UE currently works on the first BWP.

Cases after the UE receives BWP switching indication information are asfollows:

Case 1: The UE needs to perform an RA procedure. If the RA procedurecannot be performed on the second BWP, for example, no PRACH resourceused for random access is configured in the second BWP and/or no CSSused to receive an RAR is configured in the second BWP, where the secondBWP is a BWP configured by the network device for the UE, the UEinitiates the random access procedure on the first BWP. Optionally, theUE switches to the second BWP after completing the random accessprocedure.

Case 2: The UE needs to perform an RA procedure. If a bandwidth partinactivity timer of the UE triggers the UE to use the second BWP, or agNB instructs the UE to use the second BWP, and if the RA procedure canbe performed on the second BWP, for example, a PRACH resource used forrandom access is configured in the second BWP and/or a CSS used toreceive an RAR is configured in the second BWP, the UE initiates therandom access procedure on the second BWP. Optionally, the UE stops therandom access procedure on the first BWP, or the UE initiates the randomaccess procedure on the first BWP, and if the random access procedurefails, the UE initiates the random access procedure on the second BWP.

Case 3: The UE selects a BWP having relatively high numerology, toinitiate a random access procedure.

If numerology corresponding to the first BWP is relatively high, forexample, the numerology of the first BWP is higher than numerology ofthe second BWP, the UE initiates the random access procedure on thefirst BWP. Optionally, the UE switches to the second BWP aftercompleting the random access procedure.

If numerology corresponding to the second BWP is relatively high, forexample, the numerology of the second BWP is higher than numerology ofthe first BWP, the UE selects the second BWP to initiate the randomaccess procedure. Optionally, the UE stops the random access procedureon the first BWP, or the UE initiates the random access procedure on thefirst BWP, and if the random access procedure fails, the UE initiatesthe random access procedure on the second BWP.

Case 4: A gNB instructs the UE to use a BWP having relatively highnumerology, to initiate an RA procedure.

For example, numerology of the first BWP is higher than numerology ofthe second BWP, and the gNB instructs the UE to select the first BWP toinitiate the random access procedure.

For another example, numerology of the second BWP is higher thannumerology of the first BWP, and the gNB instructs the UE to select thesecond BWP to initiate the random access procedure.

Case 5: The UE selects a BWP having relatively high RA configuration, toinitiate a random access procedure.

If RA configuration corresponding to the first BWP is relatively high,and is higher than RA configuration of the second BWP, the UE selectsthe first BWP to initiate the random access procedure. Optionally, theUE switches to the second BWP after completing the random accessprocedure.

Specifically, the RA configuration may include a backoff parameter(Backoff parameter) and a power (power). For example, if a backoffparameter on the first BWP is less than a backoff parameter on thesecond BWP, it may be considered that the RA configuration of the firstBWP is higher than the RA configuration of the second BWP.Alternatively, for example, if a power on the first BWP is less than apower on the second BWP, it may be considered that the RA configurationof the first BWP is higher than the RA configuration of the second BWP.

If RA configuration corresponding to the second BWP is relatively high,and is higher than RA configuration of the first BWP, the UE selects thesecond BWP to initiate the random access procedure. Optionally, the UEstops the random access procedure on the first BWP, or the UE initiatesthe random access procedure on the first BWP, and if the current roundof random access procedure fails, the UE initiates the random accessprocedure on the second BWP.

Case 6: A gNB instructs the UE to use a BWP having relatively high RAconfiguration, to initiate RA. For example, RA configuration of thefirst BWP is higher than RA configuration of the second BWP, and the gNBinstructs the UE to select the first BWP to initiate the random accessprocedure.

For another example, RA configuration of the second BWP is higher thanRA configuration of the first BWP, and the gNB instructs the UE toselect the second BWP to initiate the random access procedure.

Case 7: The UE selects a BWP in which a non-contention-based PRACHresource is configured, to initiate an RA procedure.

If the non-contention-based PRACH resource is configured in the firstBWP, the UE selects the first BWP to initiate the random accessprocedure. Optionally, the UE switches to the second BWP aftercompleting the random access procedure.

If the non-contention-based PRACH resource is configured in the secondBWP, the UE selects the second BWP to initiate the random accessprocedure. Optionally, the UE stops the random access procedure on thefirst BWP, or the UE initiates the random access procedure on the firstBWP, and if the current round of random access procedure fails, the UEinitiates the random access procedure on the second BWP.

Case 8: A gNB instructs the UE to use a BWP in which anon-contention-based PRACH resource is configured, to initiate an RAprocedure.

For example, if the non-contention-based PRACH resource is configured inthe first BWP, the gNB instructs the UE to select the first BWP toinitiate the random access procedure.

For another example, if the non-contention-based PRACH resource isconfigured in the second BWP, the gNB instructs the UE to select thesecond BWP to initiate the random access procedure.

Case 9: A counter corresponding to SR configuration of the UE reaches alargest value (it may be referred to as an SR failure), the UE uses aBWP corresponding to a logical channel (logical channel, LCH)corresponding to the SR configuration, to initiate a random accessprocedure, and in this case, the SR configuration corresponds to theLCH, and the LCH corresponds to the BWP.

For example, the LCH corresponding to the SR configuration correspondsto the first BWP, and the UE selects the first BWP to initiate therandom access procedure.

Alternatively, for another example, the LCH corresponding to the SRconfiguration corresponds to the second BWP, and the UE selects thesecond BWP to initiate the random access procedure. Optionally, the UEstops the random access procedure on the first BWP, or the UE initiatesthe random access procedure on the first BWP, and if the random accessprocedure fails, the UE initiates the random access procedure on thesecond BWP.

Case 10: The UE uses a BWP corresponding to an LCH having buffer data(buffer data), to initiate a random access procedure, and if a pluralityof LCHs have buffer data, the UE selects a BWP corresponding to an LCH,to initiate the random access procedure.

For example, the first BWP is selected according to random accessconfiguration corresponding to an LCH having buffer data, and the UEselects the first BWP to initiate the random access procedure.

For another example, the second BWP is selected according to randomaccess configuration corresponding to an LCH having buffer data, and theUE selects the second BWP to initiate the random access procedure.Optionally, the UE stops the random access procedure on the first BWP,or the UE initiates the random access procedure on the first BWP, and ifthe random access procedure fails, the UE initiates the random accessprocedure on the second BWP.

Case 11: The UE selects a BWP according to random access configurationcorresponding to an LCH having buffer data, to initiate a random accessprocedure.

For example, the first BWP is selected according to random accessconfiguration corresponding to an LCH having buffer data, and the UEselects the first BWP to initiate the random access procedure.

For another example, the second BWP is selected according to randomaccess configuration corresponding to an LCH having buffer data, and theUE selects the second BWP to initiate the random access procedure.Optionally, the UE stops the random access procedure on the first BWP,or the UE initiates the random access procedure on the first BWP, and ifthe random access procedure fails, the UE initiates the random accessprocedure on the second BWP.

Case 12: The UE selects an LCH based on a priority of an LCH havingbuffer data, and uses a BWP corresponding to the LCH, to initiate arandom access procedure.

For example, the UE selects an LCH based on a priority of an LCH havingbuffer data, and uses the first BWP corresponding to the LCH, toinitiate the random access procedure.

For another example, the UE selects an LCH based on a priority of an LCHhaving buffer data, and uses the second BWP corresponding to the LCH, toinitiate the random access procedure. Optionally, the UE stops therandom access procedure on the first BWP, or the UE initiates the randomaccess procedure on the first BWP, and if the random access procedurefails, the UE initiates the random access procedure on the second BWP.

Case 13: The UE selects a corresponding BWP based on a priority of aparameter that is of a random access procedure and that is configuredfor an LCH having buffer data, to initiate a random access procedure.

For example, the UE selects the first BWP based on the priority of theparameter that is of the random access procedure and that is configuredfor the LCH having buffer data, to initiate the random access procedure.

For another example, the UE selects the second BWP based on the priorityof the parameter that is of the random access procedure and that isconfigured for the LCH having buffer data, to initiate the random accessprocedure.

Optionally, the UE stops the random access procedure on the first BWP,or the UE initiates the random access procedure on the first BWP, and ifthe random access procedure fails, the UE initiates the random accessprocedure on the second BWP.

Case 14: The UE initiates a random access procedure. If the UE uses thefirst transmit beam on the first BWP, the UE switches to the secondtransmit beam on the second BWP, and the second transmit beam can cover(cover) the first BWP, the UE selects the first BWP to initiate therandom access procedure. If the second transmit beam cannot cover thefirst BWP, the UE selects the second BWP to initiate the random accessprocedure.

Optionally, the UE stops the random access procedure on the first BWP,or the UE initiates the random access procedure on the first BWP, and ifthe random access procedure fails, the UE initiates the random accessprocedure on the second BWP.

Case 15: The UE switches back to a default BWP to perform an RAprocedure. An active first BWP pair of the UE after the RA procedure iscompleted is a default BWP pair, or the UE switches back to the originalfirst BWP pair after the RA procedure is completed.

The default BWP may be the initial BWP.

It should be noted that priorities of LCHs, or priorities of parameters,or random access procedure configuration may be distinguished based onone or more of QoS, a service, a latency latency (latency), stringent(stringent), a transmission time interval (transmission time interval,TTI) length, a data waiting time, and the like.

Optionally, before the UE initiates RA, the gNB notifies the UE of oneor more of the following: which BWP has a PRACH resource, an SS block,and the like, for example, a PRACH resource used for random access isconfigured in the first BWP, and no PRACH resource used for randomaccess is configured in the second BWP, or a PRACH resource used forrandom access is configured in each of the first BWP and the second BWP,but the BWPs correspond to different numerology, or a contention-basedPRACH resource is configured in the first BWP, and anon-contention-based PRACH resource is configured in the second BWP; orthe gNB notifies the UE of a BWP corresponding to an LCH of the UE. ThegNB may notify the UE of the foregoing information by using RRC, a SIB,or the like.

Optionally, the gNB configures a PRACH resource, and the gNB allocatesPRACH resources of different UEs to different BWPs, and may specificallyallocate the PRACH resources based on QoS required by the UE.

Optionally, the UE initiates the random access procedure on the firstBWP. The UE does not perform deactivation (deactivate), for example, astate machine (state machine) of the UE is not set to be deactivated(deactivate). After completing RA on the first BWP, the UE deactivatesthe BWP, for example, the state machine of the UE is set to bedeactivated.

Optionally, the UE switches to the second BWP after completing a randomprocedure.

Optionally, the UE initiates the random access procedure on the firstBWP, a BWP inactivity timer maintained by the UE stops, and aftercompleting the RA on the first BWP, the UE switches to the second BWP(for example, a default BWP).

Optionally, the UE initiates the random access procedure on the firstBWP, and continues to use (does not initialize) a parameter used by theUE, for example, a power ramping counter (counter of power ramping) or abackoff parameter. For example, a value of the counter is X, and the UEcontinues to use the counter based on X (for example, X remainsunchanged, or X is increased by 1). For example, a value of the backoffparameter is Y, and the UE continues to use the backoff parameter basedon Y.

For example, the UE selects a random backoff time random backoff timebased on the backoff parameter (for example, the value is Y), and thefirst user equipment reinitiates the random access procedure to thenetwork device after the random backoff time.

For example, when the UE does not change a Tx beam, the power rampingcounter continues to count, for example, X is increased by 1. When theUE changes a Tx beam, the power ramping counter remains unchanged, forexample, X remains unchanged.

Optionally, the UE initiates the random access procedure on the secondBWP, and continues to use (does not initialize) a parameter used by theUE, for example, a power ramping counter or a backoff parameter. Forexample, a value of the counter is X, and the UE continues to use thecounter based on X. For example, a value of the backoff parameter is Y,and the UE continues to use the backoff parameter based on Y.

For example, the UE selects a random backoff time random backoff timebased on the backoff parameter (for example, the value is Y), and thefirst user equipment reinitiates the random access procedure to thenetwork device after the random backoff time.

For example, when the UE does not change a Tx beam, the power rampingcounter continues to count, for example, X is increased by 1. When theUE changes a Tx beam, the power ramping counter remains unchanged, forexample, X remains unchanged.

Alternatively, the UE initiates the random access procedure on thesecond BWP, and initializes a parameter used by the UE, for example, apower ramping counter and/or a backoff parameter. For example, thecounter is set to an initial value (for example, the initial value is 0or 1). For example, a value of the backoff parameter is an initial value(for example, the initial value is a value in a backoff indicator(backoff indicator, BI) in an RAR, or is 0 ms).

For example, the UE selects a random backoff time random backoff timebased on the backoff parameter (the initial value), and the first userequipment reinitiates the random access procedure to the network deviceafter the random backoff time.

For example, when the UE does not change a Tx beam, the power rampingcounter continues to count, for example, the initial value is increasedby 1. When the UE changes a Tx beam, the power ramping counter remainsunchanged, for example, the initial value remains unchanged.

Optionally, the UE initiates the random access procedure on the secondBWP, and does not change a parameter used by the UE, for example, thefirst transmit beam used by the UE. In other words, the UE uses thefirst transmit beam on the first BWP, and still uses the first transmitbeam on the second BWP.

Alternatively, the UE initiates the random access procedure on thesecond BWP, and changes a parameter used by the UE, for example, thefirst transmit beam used by the UE. In other words, the UE uses thefirst transmit beam on the first BWP, and still uses the second transmitbeam on the second BWP.

Optionally, the UE initiates the random access procedure on the secondBWP, and does not change a first transmit beam of the gNB selected bythe UE. In other words, the UE selects the first transmit beam of thegNB on the first BWP, and still selects the first transmit beam of thegNB on the second BWP.

Further, if the UE supports a beam correspondence (correspondence), theUE correspondingly selects a transmit beam of the UE. In other words,there is a correspondence between the first transmit beam of the gNB anda first transmit beam of the UE, and the UE correspondingly selects thefirst transmit beam of the UE.

Alternatively, the UE initiates the random access procedure on thesecond BWP, and changes a first transmit beam of the gNB selected by theUE. In other words, the UE selects the first transmit beam of the gNB onthe first BWP, and still selects the second transmit beam of the gNB onthe second BWP.

Further, if the UE supports a beam correspondence, the UEcorrespondingly selects a transmit beam of the UE. In other words, thereis a correspondence between the second transmit beam of the gNB and asecond transmit beam of the UE, and the UE correspondingly selects thesecond transmit beam of the UE.

In this application, that the UE works on a BWP means that the UE uses aresource corresponding to the BWP. For example, the resourcecorresponding to the BWP includes at least one of an uplink resource anda downlink resource. For example, that the UE initiates random access onthe first BWP means that the UE uses a resource corresponding to thefirst BWP, to initiate random access. For another example, that the UEinitiates random access on the second BWP means that the UE uses aresource corresponding to the second BWP, to initiate random access. Foranother example, that the UE switches to the second BWP means that theUE uses a resource corresponding to the second BWP. For another example,that the UE switches to the first BWP means that the UE uses a resourcecorresponding to the first BWP.

In this application, that the UE initiates random access may be directlyreplaced with that the UE performs random access, and details are notdescribed in this application. For example, that the UE initiates randomaccess on the first BWP may be replaced with that the UE performs randomaccess on the first BWP. For another example, for example, that the UEinitiates random access on the second BWP may be replaced with that theUE performs random access on the second BWP.

It should be noted that, that the UE performs a random access procedureon a BWP means that the UE sends a message in an access procedure byusing a resource in the BWP, for example, a preamble, and/or a thirdmessage in the random access procedure.

In addition, that the UE switches the first BWP means that the UE nolonger uses a resource corresponding to the first BWP. For example,switching a first uplink BWP means that a resource corresponding to thefirst uplink BWP is no longer used. For example, switching a firstdownlink BWP means that a resource corresponding to the first downlinkBWP is no longer used. For example, switching the first uplink BWP andthe first downlink BWP means that the resource corresponding to thefirst uplink BWP and the resource corresponding to the first downlinkBWP are no longer used.

Switching to the second BWP means that a resource corresponding to thesecond BWP is used. For example, switching to a second uplink BWP meansthat a resource corresponding to the second uplink BWP is used. Forexample, switching to a second downlink BWP means that a resourcecorresponding to the second downlink BWP is used. For example, switchingto the second uplink BWP and the second downlink BWP means that theresource corresponding to the second uplink BWP and the resourcecorresponding to the second downlink BWP are used.

It should be noted that, that a transmit beam of the user equipmentcovers a BWP may be alternatively referred to as that the transmit beamof the user equipment can reach the gNB on the BWP.

That the second transmit beam can cover the first BWP may bealternatively referred to as that the second transmit beam can reach thegNB on the first BWP. If the UE uses the second transmit beam, that thesecond transmit beam cannot cover the second BWP may be alternativelyreferred to as that the second transmit beam cannot reach the gNB on thesecond BWP. That a transmit beam of the user equipment can reach thenetwork device on a BWP may be alternatively referred to as that thetransmit beam of the user equipment can cover the network device on theBWP.

For example, that the first transmit beam of the user equipment canreach the network device on the first BWP may be alternatively referredto as that the first transmit beam of the user equipment can cover thenetwork device on the first BWP.

That the transmit beam of the user equipment cannot reach the networkdevice on the BWP may be alternatively referred to as that the transmitbeam of the user equipment cannot cover the network device on the BWP,or that a beam failure (beam failure) occurs in the transmit beam of theuser equipment.

For example, that the first transmit beam of the user equipment cannotreach the network device on the first BWP may be alternatively referredto as that the first transmit beam of the user equipment cannot coverthe network device on the first BWP, or that a beam failure occurs inthe first transmit beam.

It should be noted that the first BWP may include a first uplink BWP,and the second BWP may include a first uplink BWP. Alternatively, thefirst BWP may include a first downlink BWP, and the second BWP mayinclude a second downlink BWP. Alternatively, the first BWP may includea first uplink BWP and a first downlink BWP, and the second BWP mayinclude a second uplink BWP and a second downlink BWP. Alternatively,the first BWP may include a first uplink BWP, and the second BWP mayinclude a second downlink BWP. Alternatively, the first BWP may includea first downlink BWP, and the second BWP may include a second uplinkBWP.

A BWP pair may be alternatively referred to as a BWP, and the BWPincludes an uplink BWP and a downlink BWP.

The first BWP may be alternatively referred to as a first BWP pair, andthe first BWP includes the first uplink BWP and the first downlink BWP.

The second BWP may be alternatively referred to as a second BWP pair,and the second BWP includes the second uplink BWP and the seconddownlink BWP.

The initial BWP may be alternatively referred to as an initial BWP pair,and the initial BWP includes an initial uplink BWP and an initialdownlink BWP.

The default BWP may be alternatively referred to as a default BWP pair,and the default BWP includes a default uplink BWP and a default downlinkBWP.

Further, when the user equipment performs the random access procedure onthe first BWP, or before the user equipment performs the random accessprocedure on the first BWP, or after the user equipment performs therandom access procedure on the first BWP, the user equipment receivesthe BWP switching indication information sent by the network device, orthe bandwidth part inactivity timer of the user triggers the userequipment to use the second BWP.

Further, the user equipment initiates the random access procedurebefore, when, or after the user equipment uses the second BWP. Forexample, if the second BWP meets the condition for performing a randomaccess procedure, the user equipment performs the random accessprocedure on the second BWP, or if the first BWP meets the condition forperforming a random access procedure, the user equipment performs therandom access procedure on the first BWP, or if the second BWP does notmeet the condition for performing a random access procedure, the userequipment performs the random access procedure on the first BWP, or ifthe first BWP does not meet the condition for performing a random accessprocedure, the user equipment performs the random access procedure onthe second BWP.

It should be noted that, that the UE performs the random accessprocedure may be that the gNB instructs the UE to perform RA, or the UEneeds to initiate RA when the counter corresponding to the SRconfiguration scheduling request configuration of the UE reaches thelargest value, or the UE is out of synchronization, or a radio linkfailure occurs, or the UE needs establish an RRC radio resource controlconnection to the gNB.

It is further noted that a random access priority may be alternativelyreferred to as a random access adjustment parameter. The UE uses arandom access adjustment parameter corresponding to a BWP, and adjustsat least one of the following based on at least the random accessadjustment parameter corresponding to the BWP: the backoff parameter,the power increment value, the power ramping counter, and the preamblecounter. For example, the UE uses an RA adjustment parametercorresponding to the first BWP, and adjusts at least one of thefollowing based on at least the random access adjustment parametercorresponding to the first BWP: the backoff parameter, the powerincrement value, the power ramping counter, and the preamble counter.For example, the UE uses an RA adjustment parameter corresponding to thesecond BWP, and adjusts at least one of the following based on at leastthe random access adjustment parameter corresponding to the second BWP:the backoff parameter, the power increment value, the power rampingcounter, and the preamble counter. For example, the UE uses an RAadjustment parameter corresponding to the initial BWP, and adjusts atleast one of the following based on at least the random accessadjustment parameter corresponding to the initial BWP: the backoffparameter, the power increment value, the power ramping counter, and thepreamble counter.

It is further noted that completing a random access procedure on a BWPmay be that the random access procedure succeeds, or that the randomaccess procedure fails, or that the user equipment successfullycompletes the random access procedure on the BWP, or that the userequipment successfully completes the random access procedure on the BWP,but the user equipment fails in access, or that the user equipmentsuccessfully accesses the network device, and the user equipment failsin access.

Specifically, the user equipment performs the random access procedure onthe first BWP, and does not deactivate the first BWP, or the userequipment keeps the first BWP activated, or the user equipment stops thebandwidth part inactivity timer used to maintain the first BWP, or theuser equipment deactivates the first BWP after the user equipmentperforms the random access procedure on the first BWP.

It should be noted that, that the UE works on the first BWP isspecifically: sending information on an uplink shared channel (uplinkshare channel, UL-SCH), sending information on a random access channel(random access channel, RACH), receiving information on a downlinkshared channel (downlink share channel, DL-SCH), receiving informationon a physical downlink control channel (Physical Downlink ControlChannel, PDCCH), for example, downlink control information (downlinkcontrol information, DCI) information, and sending information on aphysical uplink control channel (Physical uplink Control Channel,PUCCH), for example, downlink control information (uplink controlinformation, UCI) information.

In this application, that a resource used for random access is availablein a BWP may be specifically that the resource used for random accessexists in an uplink BWP of the BWP. For example, that a resource usedfor random access is available in the first BWP is specifically that theresource used for random access exists in a first uplink BWP of thefirst BWP. Optionally, for example, that a resource used for randomaccess is available in the second BWP is specifically that the resourceused for random access exists in a second uplink BWP of the second BWP.Optionally, for example, a resource used for random access is availablein an initial BWP is specifically that the resource used for randomaccess exists in an initial uplink BWP of the initial BWP.

Further, that no resource used for random access is configured in a BWPmay be specifically that no resource used for random access isconfigured in an uplink BWP of the BWP. For example, no resource usedfor random access is configured in the first BWP. For another example,no resource used for random access is configured in a first uplink BWPof the first BWP.

In this application, the initial BWP is indicated by the network devicein system information. Further, the initial BWP is configured under alimitation of a capability of the UE device.

The performing, by the UE, the random access procedure on an initial BWPis specifically performing a contention-based random access procedure.

Specifically, keeping the first BWP activated includes keeping the firstuplink BWP activated, and/or keeping the first downlink BWP activated.

Optionally, skipping deactivating the first BWP includes skippingdeactivating the first uplink BWP, and/or skipping deactivating thefirst downlink BWP.

For example, the UE keeps the first BWP in a state.

Optionally, keeping the first BWP in an activated state includes keepingthe first uplink BWP in an activated state, and/or keeping the firstdownlink BWP in an activated state.

Optionally, skipping deactivating the state of the first BWP includesskipping deactivating the state of the first uplink BWP, and/or skippingdeactivating the state of the first downlink BWP.

It is further noted that the bandwidth part inactivity timer may bealternatively referred to as a BWP timer, and a function is to triggerthe user equipment to switch a non-default BWP to a default BWP.

Optionally, the non-default BWP is different from the default BWP. Forexample, a non-default uplink BWP is different from the default uplinkBWP, and/or a non-default downlink BWP is different from the defaultdownlink BWP.

Optionally, the first BWP is used as an example of the non-default BWP.For example, the UE works on the first BWP, and the UE switches thefirst BWP to the default BWP when the bandwidth part inactivity timerreaches a time or expires or times out (for example, reaches the largestvalue or a smallest value). Optionally, that the UE switches the firstBWP to the default BWP may be specifically that the UE switches thefirst downlink BWP to the default downlink BWP, or that the UE switchesthe first uplink BWP and the first downlink BWP to the default uplinkBWP and the default downlink BWP.

Optionally, a bandwidth part inactivity timer used to maintain thenon-default BWP may be a bandwidth part inactivity timer used tomaintain the non-default downlink BWP. For example, the bandwidth partinactivity timer used to maintain the first BWP may be a bandwidth partinactivity timer used to maintain the first downlink BWP.

Optionally, the bandwidth part inactivity timer used to maintain thenon-default downlink BWP may be alternatively referred to as thebandwidth part inactivity timer corresponding to the non-default BWP.For example, the bandwidth part inactivity timer used to maintain thefirst BWP may be alternatively referred to as the bandwidth partinactivity timer corresponding to the first BWP. For another example,the bandwidth part inactivity timer used to maintain the first downlinkBWP may be alternatively referred to as the bandwidth part inactivitytimer corresponding to the first downlink BWP.

Optionally, the bandwidth part inactivity timer used to maintain thenon-default BWP may be alternatively referred to as the bandwidth partinactivity timer applied to the non-default BWP. For example, thebandwidth part inactivity timer used to maintain the first BWP may bealternatively referred to as the bandwidth part inactivity timer appliedto the first BWP. For another example, the bandwidth part inactivitytimer used to maintain the first downlink BWP may be alternativelyreferred to as the bandwidth part inactivity timer applied to the firstdownlink BWP.

Optionally, the bandwidth part inactivity timer starts timing when thenon-default BWP works. For example, the bandwidth part inactivity timerstarts timing when the first BWP works.

Optionally, the default BWP may be the initial BWP.

Optionally, that the UE device works on the first BWP may be that thenetwork device schedules the UE to the first BWP. For example, thenetwork device hands over the UE from the initial BWP to the first BWP.

In this application, setting the backoff parameter to the value in thebackoff indicator is specifically that the UE switches to the secondBWP, and sets the backoff parameter to a value in a backoff indicatorreceived on the second BWP; or that the UE switches to the initial BWP,and sets the backoff parameter to a value in a backoff indicatorreceived on the initial BWP.

After completing the RA procedure on the initial BWP, the UE waits forthe network device to send the BWP switching indication information.

Further, the UE performs BWP switching after receiving the BWP switchingindication information on the initial BWP.

In this application, a power increment value is adjusted. For example, apower ramping step power ramping step is adjusted.

Optionally, a power increment value corresponding to a high priority isgreater than a power increment value corresponding to a low priority.For example, a first priority is higher than a second priority, and apower increment value corresponding to the first priority is greaterthan a power increment value corresponding to the second priority.

Optionally, a power ramping counter (power ramping counter) is adjusted.For example, a total quantity of times that a power can be increased isadjusted, or a value of the power ramping counter is adjusted, or alargest value of the power ramping counter is adjusted.

Optionally, a preamble counter is adjusted. For example, a totalquantity of times that a preamble can be sent is adjusted, or a value ofthe preamble counter is adjusted, or a largest value of the preamblecounter is adjusted.

Optionally, the BWP switching indication information is used to instructthe UE to use the second BWP, or the BWP switching indicationinformation is used to instruct the UE to switch to the second BWP.Optionally, the second BWP is different from the first BWP, and thesecond BWP is a BWP indicated by the network device, namely, a targetBWP that is indicated by the network device and that the UE needs to use(activate or switch to).

Optionally, that the second BWP is the BWP indicated by the networkdevice may be specifically that the network device indicates identityinformation (for example, an index index or other identity information)of the BWP to the UE. The UE switches to the corresponding BWP or usesthe corresponding BWP according to the identity information (forexample, the index) of the BWP. For example, the UE works on the firstBWP, the network device indicates an index of the second BWP to the UE,and the UE switches to the second BWP or uses the second BWP accordingto the index of the second BWP.

Optionally, the first BWP includes the first uplink BWP and the firstdownlink BWP, and the performing, by the UE, the random access procedureon the first BWP includes: using, by the UE, the first uplink BWP andthe first downlink BWP, to perform the random access procedure. Forexample, the UE uses the first uplink BWP to send a preamble preamble,and the UE uses the first downlink BWP to receive a random accessresponse RAR message sent by the network device.

Optionally, the second BWP includes the second uplink BWP and the seconddownlink BWP, and the performing, by the UE, the random access procedureon the second BWP includes: using, by the UE, the second uplink BWP andthe second downlink BWP, to perform the random access procedure. Forexample, the UE uses the second uplink BWP to send a preamble, and theUE uses the second downlink BWP to receive an RAR message sent by thenetwork device. Optionally, the initial BWP includes the initial uplinkBWP and the initial downlink BWP, and the performing, by the UE, therandom access procedure on an initial BWP includes: using, by the UE,the initial uplink BWP and the initial downlink BWP, to perform therandom access procedure. For example, the UE uses the initial uplink BWPto send a preamble, and the UE uses the initial downlink BWP to receivean RAR message sent by the network device.

According to the foregoing solution, it is uncertain whether a BWP onwhich the UE currently works has a PRACH resource, and it is uncertainwhere the UE performs RA. If a random access resource and/or a CSSare/is configured in a BWP, the UE may clearly initiate RA on thespecific BWP, or otherwise, the UE does not learn a location of sendinguplink information. In addition, it is specified that downlinkinformation is received on a downlink BWP, or otherwise, the UE does notlearn a location of receiving a PDCCH and receiving an RAR. The UE maycomplete the RA procedure on a currently active BWP based on differentcases, and further set, on the current BWP, a related parameter needingto be used. Alternatively, the UE switches to the second BWP to completethe RA procedure, and further sets, on the second BWP, a relatedparameter needing to be used. Specifically, a timer is stopped, toprevent uncertainty of whether the UE switches a BWP when the timer istriggered during the RA procedure, and better implement interworking.The BWP is kept in an activated state, to ensure consistency with astate machine of the UE, and prevent inconsistency between behaviorperformed by the UE in different states. Advantages of continuing toperform RA on the current BWP, and continuing to use the used parameterssuch as the value of the power ramping counter and the backoff parameterare as follows: Inappropriate impact caused to a system because theparameters of the UE device change is prevented, interference caused toa network is avoided, and unfair contention is avoided. The firsttransmit beam continues to be used, so that an access procedure of theUE can be accelerated. The second transmit beam is switched to for use,so that the UE can obtain a better reception gain. Advantages ofinitializing the parameters used for RA such as the value of the powerramping counter and the backoff parameter are as follows: The equipmentmay not need to maintain the parameters, and compatibility with theoriginal RA procedure can be avoided. The foregoing solution can meet arequirement of a standard setting, reduce interference to the network,and implement interworking.

Example 5

The gNB instructs the UE to initiate an RA procedure.

For example, the gNB sends a PDCCH order to trigger the UE to initiatethe RA procedure. Specifically, an indication may be performed by usinga DCI format 1A, where CRC of the DCI format 1A is scrambled by using aC-RNTI.

The gNB instructs the UE to initiate the RA procedure. In addition, thegNB indicates an uplink BWP used by the UE. Optionally, the uplink BWPis used by the UE to send a preamble. A resource in the uplink BWP maybe contention-based, or may be non-contention-based.

Optionally, the gNB may indicate, in a PRACH mask index field, an indexof the uplink BWP used by the UE, or the gNB sends DCI and indicates, inthe DCI, an index of the uplink BWP used by the UE.

Optionally, the gNB instructs the UE to initiate the RA procedure. Inaddition, the gNB indicates a downlink BWP used by the UE. Optionally,the downlink BWP is used by the UE to receive an RAR and/or an Msg4.

Optionally, the gNB may indicate, in a PRACH mask index field, an indexof the uplink BWP used by the UE, or the gNB sends DCI and indicates, inthe DCI, an index of the uplink BWP used by the UE.

The UE receives information about an indicated BWP (including at leastone of an uplink BWP and a downlink BWP) and an indication that is sentby the gNB and that is used to initiate RA. The UE initiates the RAprocedure on the indicated BWP.

In this way, when instructing the UE to initiate the RA procedure, thegNB instructs the UE to perform RA on a corresponding BWP, so that theUE selects an appropriate PRACH resource. The gNB may also learn a BWPon which the UE performs RA, facilitating determining performed by thegNB.

Example 6

The UE works on the first BWP. The UE initiates a random accessprocedure. The UE sends a preamble preamble on a default UL BWP. Thedefault UL BWP is configured by the gNB, and may be the initial BWP.

Optionally, after sending the preamble, the UE switches back to thefirst BWP.

After receiving the preamble sent by the UE, the gNB instructs, on adefault DL BWP, the UE to receive an RAR message on the second BWP.

Alternatively, the gNB instructs, on the first downlink BWP of the firstBWP, the UE to receive an RAR message on the second BWP.

Alternatively, the gNB instructs, on the first downlink BWP of the firstBWP, the UE to receive an RAR message on the first BWP.

Alternatively, the gNB instructs, on a default DL BWP, the UE to receivean RAR message on the first BWP. Optionally, the UE sends a thirdmessage in the random access procedure on the default UL BWP. Afterreceiving the third message sent by the UE, the gNB instructs, on thedefault DL BWP, the UE to receive a fourth message in the random accessprocedure on the second BWP. Alternatively, the gNB instructs, on thedownlink BWP of the first BWP, the UE to receive a fourth message in therandom access procedure on the second BWP. Alternatively, the gNBinstructs, on the downlink BWP of the first BWP, the UE to receive afourth message in the random access procedure on the first BWP.Alternatively, the gNB instructs, on the default DL BWP, the UE toreceive a fourth message in the random access procedure on the firstBWP.

Example 7

A random access method, applied to UE, where the method includes:working, by the UE, on a BWP, where the method further includes any oneof the following: the UE receives BWP switching indication informationsent by a network device, where the switching indication information isused to instruct the UE to use a second BWP, or a bandwidth partinactivity timer of the user triggers the UE to use a second BWP; andthe UE performs a random access procedure on the first BWP if the firstBWP meets a condition for performing a random access procedure; or theUE performs a random access procedure on the second BWP if the secondBWP meets a condition for performing a random access procedure; or theUE performs a random access procedure on the second BWP if the first BWPdoes not meet a condition for performing a random access procedure; orthe UE performs a random access procedure on the first BWP if the secondBWP does not meet a condition for performing a random access procedure;or if a default default BWP meets a condition for performing a randomaccess procedure, the UE performs a random access procedure on thedefault BWP; or if the first BWP does not meet a condition forperforming a random access procedure, the UE performs a random accessprocedure on the default BWP, or the UE performs a contention-basedrandom access procedure on the default BWP; or if the first BWP meets acondition for performing a random access procedure, and the second BWPmeets the condition for performing a random access procedure, the UEchooses, based on a predetermined rule, to perform a random accessprocedure on the first BWP, or to perform a random access procedure onthe second BWP.

Optionally, the UE performs the random access procedure on the secondBWP if the first BWP does not meet the condition for performing a randomaccess procedure; or the UE performs the random access procedure on thefirst BWP when the second BWP does not meet the condition for performinga random access procedure.

That the first BWP does not meet the condition for performing a randomaccess procedure includes at least any one of the following: no resourceused for random access is configured in the first BWP; no common searchspace CSS used to receive a random access response RAR is configured inthe first BWP; a first transmit beam of the UE cannot reach the networkdevice on the first BWP, and the first transmit beam is a transmit beamused by the UE on the first BWP; the UE switches from the first transmitbeam to the second transmit beam, the second transmit beam of the UEcannot reach the network device on the first BWP, and the first transmitbeam is a transmit beam used by the UE on the first BWP; a countercorresponding to scheduling request configuration of the UE reaches alargest value, and an LCH logical channel corresponding to thescheduling request configuration corresponds to the second BWP; and anLCH logical channel corresponding to the first BWP does not have bufferdata.

That the second BWP does not meet the condition for performing a randomaccess procedure includes at least any one of the following: no resourceused for random access is configured in the second BWP; no common searchspace CSS used to receive a random access response RAR is configured inthe second BWP; the first transmit beam of the UE cannot reach thenetwork device on the second BWP, and the first transmit beam is atransmit beam used by the UE on the first BWP; the UE switches from thefirst transmit beam to the second transmit beam, the second transmitbeam of the UE cannot reach the network device on the second BWP, andthe first transmit beam is a transmit beam used by the UE on the firstBWP; the counter corresponding to the scheduling request configurationof the UE reaches the largest value, and the LCH logical channelcorresponding to the scheduling request configuration corresponds to thefirst BWP; and the LCH logical channel corresponding to the second BWPdoes not have buffer data.

Optionally, the method further includes: performing, by the UE, therandom access procedure on the first BWP if the first BWP meets thecondition for performing a random access procedure; or performing, bythe UE, the random access procedure on the second BWP if the second BWPmeets the condition for performing a random access procedure; orperforming, by the UE, the random access procedure on the second BWP ifthe first BWP does not meet the condition for performing a random accessprocedure; or performing, by the UE, the random access procedure on thefirst BWP if the second BWP does not meet the condition for performing arandom access procedure; or performing, by the UE, the random accessprocedure on the default BWP if the default default BWP meets thecondition for performing a random access procedure.

That the first BWP meets the condition for performing a random accessprocedure includes at least any one of the following: a resource usedfor random access is available in the first BWP; a common search spaceCSS used to receive a random access response RAR is available in thefirst BWP; the first transmit beam of the UE can reach the networkdevice on the first BWP, and the first transmit beam is a transmit beamused by the UE on the first BWP; the UE switches from the first transmitbeam to the second transmit beam, the second transmit beam of the UE canreach the network device on the first BWP, and the first transmit beamis a transmit beam used by the UE on the first BWP; the countercorresponding to the scheduling request configuration of the UE reachesthe largest value, and the LCH logical channel corresponding to thescheduling request configuration corresponds to the first BWP; and theLCH logical channel corresponding to the first BWP has buffer data.

That the second BWP meets the condition for performing a random accessprocedure includes at least any one of the following: a resource usedfor random access is available in the second BWP; a common search spaceCSS used to receive a random access response RAR is available in thesecond BWP; the first transmit beam of the UE can reach the networkdevice on the second BWP, and the first transmit beam is a transmit beamused by the UE on the first BWP; the UE switches from the first transmitbeam to the second transmit beam, the second transmit beam of the UE canreach the network device on the second BWP, and the first transmit beamis a transmit beam used by the UE on the first BWP; the countercorresponding to the scheduling request configuration of the UE reachesthe largest value, and the LCH logical channel corresponding to thescheduling request configuration corresponds to the second BWP; and theLCH logical channel corresponding to the second BWP has buffer data.

That the default BWP meets the condition for performing a random accessprocedure includes at least any one of the following: a resource usedfor random access is available in the default BWP; a common search spaceCSS used to receive a random access response RAR is available in thedefault BWP; the first transmit beam of the UE can reach the networkdevice on the default BWP, and the first transmit beam is a transmitbeam used by the UE on the first BWP; the UE switches from the firsttransmit beam to the second transmit beam, the second transmit beam ofthe UE can reach the network device on the default BWP, and the firsttransmit beam is a transmit beam used by the UE on the first BWP; thecounter corresponding to the scheduling request configuration of the UEreaches the largest value, and the LCH logical channel corresponding tothe scheduling request configuration corresponds to the default BWP; andthe LCH logical channel corresponding to the default BWP has bufferdata.

Optionally, the choosing, by the UE based on a predetermined rule, toperform a random access procedure on the first BWP, or to perform arandom access procedure on the second BWP includes any one of thefollowing: the UE chooses to perform the random access procedure on thefirst BWP if numerology numerology corresponding to the first BWP ishigher than numerology corresponding to the second BWP; the UE choosesto perform the random access procedure on the first BWP if a randomaccess configuration priority corresponding to the first BWP is higherthan a random access configuration priority corresponding to the secondBWP; the UE chooses to perform the random access procedure on the firstBWP if a non-contention-based random access resource is available in thefirst BWP; the UE chooses to perform the random access procedure on thefirst BWP if the counter corresponding to the scheduling requestconfiguration of the UE reaches the largest value, and the LCH logicalchannel corresponding to the scheduling request configurationcorresponds to the first BWP; the UE chooses to perform the randomaccess procedure on the first BWP if the LCH logical channelcorresponding to the first BWP has buffer data; the UE chooses toperform the random access procedure on the first BWP if the LCH logicalchannel corresponding to the first BWP has buffer data, the LCH logicalchannel corresponding to the second BWP has buffer data, and a priorityof the LCH logical channel corresponding to the first BWP is higher thana priority of the LCH logical channel corresponding to the second BWP;the UE chooses to perform the random access procedure on the first BWPif the LCH logical channel corresponding to the first BWP has bufferdata, the LCH logical channel corresponding to the second BWP has bufferdata, and a random access configuration priority of the LCH logicalchannel corresponding to the first BWP is higher than random accessconfiguration of the LCH logical channel corresponding to the secondBWP; if the first transmit beam of the UE cannot reach the networkdevice on the second BWP, the first transmit beam is a transmit beamused by the UE on the first BWP; if the UE switches from the firsttransmit beam to the second transmit beam, and the second transmit beamof the UE cannot reach the network device on the second BWP, the firsttransmit beam is a transmit beam used by the UE on the first BWP; the UEchooses to perform the random access procedure on the second BWP ifnumerology numerology corresponding to the second BWP is higher thannumerology corresponding to the first BWP; the UE chooses to perform therandom access procedure on the second BWP if a random accessconfiguration priority corresponding to the second BWP is higher than arandom access configuration priority corresponding to the first BWP; theUE chooses to perform the random access procedure on the second BWP if anon-contention-based random access resource is available in the secondBWP; the UE chooses to perform the random access procedure on the secondBWP if the counter corresponding to the scheduling request configurationof the UE reaches the largest value, and the LCH logical channelcorresponding to the scheduling request configuration corresponds to thesecond BWP; the UE chooses to perform the random access procedure on thesecond BWP if the LCH logical channel corresponding to the second BWPhas buffer data; the UE chooses to perform the random access procedureon the second BWP if the LCH logical channel corresponding to the firstBWP has buffer data, the LCH logical channel corresponding to the secondBWP has buffer data, and a priority of the LCH logical channelcorresponding to the second BWP is higher than a priority of the LCHlogical channel corresponding to the first BWP; the UE chooses toperform the random access procedure on the second BWP if the LCH logicalchannel corresponding to the first BWP has buffer data, the LCH logicalchannel corresponding to the second BWP has buffer data, and a randomaccess configuration priority of the LCH logical channel correspondingto the second BWP is higher than random access configuration of the LCHlogical channel corresponding to the first BWP; if the first transmitbeam of the UE cannot reach the network device on the first BWP, thefirst transmit beam is a transmit beam used by the UE on the second BWP;and if the UE switches from the first transmit beam to the secondtransmit beam, and the second transmit beam of the UE cannot reach thenetwork device on the first BWP, the first transmit beam is a transmitbeam used by the UE on the second BWP.

It is further noted that the first BWP includes a first uplink BWP, andthe second BWP includes a second uplink BWP; or the first BWP includes afirst downlink BWP, and the second BWP includes a second downlink BWP;or the first BWP includes a first uplink BWP, and the initial BWPincludes an initial uplink BWP; or the first BWP includes a firstdownlink BWP, and the initial BWP includes an initial downlink BWP; orthe first BWP includes a first uplink BWP, and the default BWP includesa default uplink BWP; or the first BWP includes a first downlink BWP,and the default BWP includes a default downlink BWP; or the first BWPincludes a first uplink BWP and a first downlink BWP; or the second BWPincludes a second uplink BWP and a second downlink BWP; or the initialBWP includes an initial uplink BWP and an initial downlink BWP; or thedefault BWP includes an initial uplink BWP and a default downlink BWP;or the first uplink BWP is different from the second uplink BWP, and/orthe first downlink BWP is different from the second downlink BWP; or thefirst uplink BWP is different from the initial uplink BWP, and/or thefirst downlink BWP is different from the initial downlink BWP; or thefirst uplink BWP is different from the default uplink BWP, and/or thefirst downlink BWP is different from the default downlink BWP.

Further, the receiving, by the UE, BWP switching indication informationsent by a network device includes that the BWP switching indicationinformation instructs the UE to switch the first uplink BWP, or thefirst downlink BWP, or the first BWP and the first downlink BWP; orinstructs the UE to use the second uplink BWP, or the second downlinkBWP, or the second uplink BWP and the second downlink BWP.

Optionally, the performing, by the UE, a random access procedure on thefirst BWP further includes: switching, by the UE, to the second BWPafter completing the random access procedure.

Optionally, the performing, by the UE, a random access procedure on thedefault BWP further includes: switching, by the UE, to the first BWPafter completing the random access procedure.

Optionally, the performing, by the UE, a random access procedure on thesecond BWP includes at least any one of the following: setting a powerramping counter of the UE to an initial value; setting the backoffparameter to an initial value, or to a value in a backoff indicatorbackoff indicator; and switching, by the UE, from the first transmitbeam to the second transmit beam.

Optionally, the performing, by the UE, the random access procedure onthe second BWP includes at least any one of the following: continuing touse a value of the power ramping counter of the UE; continuing to usethe backoff parameter; and continuing, by the UE, to use the firsttransmit beam.

Optionally, the UE receives the BWP switching indication informationsent by the network device, where the switching indication informationis used to instruct the UE to use the second BWP, or the bandwidth partinactivity timer of the user triggers the UE to use the second BWP.

Further, the UE works on the first bandwidth part BWP. When the UEperforms the random access procedure on the first BWP, or before the UEperforms the random access procedure on the first BWP, or after the UEperforms the random access procedure on the first BWP, the UE receivesthe BWP switching indication information sent by the network device,where the switching indication information is used to instruct the UE touse the second BWP, or the bandwidth part inactivity timer of the usertriggers the UE to use the second BWP.

Optionally, the UE receives the BWP switching indication informationsent by the network device, where the switching indication informationis used to instruct the UE to use the second BWP, or the bandwidth partinactivity timer of the user triggers the UE to use the second BWP; andbefore, when, or after the UE uses the second BWP, if the second BWPmeets the condition for performing a random access procedure, the UEperforms the random access procedure on the second BWP; or if the firstBWP meets the condition for performing a random access procedure, the UEperforms the random access procedure on the first BWP; or if the secondBWP does not meet the condition for performing a random accessprocedure, the UE performs the random access procedure on the first BWP;or if the first BWP does not meet the condition for performing a randomaccess procedure, the UE performs the random access procedure on thesecond BWP.

Optionally, the performing, by the UE, a random access procedure on thefirst BWP further includes: skipping, by the UE, deactivating the firstBWP, or keeping, by the UE, the first BWP activated, or stopping, by theUE, a bandwidth part inactivity timer used to maintain the first BWP.Further, the UE deactivates the first BWP after the UE performs therandom access procedure on the first BWP.

The foregoing process provides processes in which different messages ina random access procedure are sent on different BWPs, and provides aplurality of manners of implementing a random access procedure.

Based on the foregoing method embodiments, an embodiment of thisapplication provides a random access apparatus, which is correspondingto user equipment and is capable of implementing at least one of theforegoing method embodiments. Referring to FIG. 6, a random accessapparatus 600 includes a receiving unit 601 and a processing unit 602.

A random access apparatus, where the apparatus is user equipment UE, theUE includes a processing unit 602 and a receiving unit 601, the UE workson a first bandwidth part BWP, and the first BWP is a currently activeBWP.

The processing unit 602 is configured to: when the UE needs to perform arandom access procedure, if the first BWP meets a condition forperforming a random access procedure, enable the UE to perform therandom access procedure on the first BWP; or if the first BWP does notmeet a condition for performing a random access procedure, enable the UEto perform the random access procedure on an initial BWP.

The receiving unit 601 is configured to: when the UE performs the randomaccess procedure on the first BWP, receive BWP switching indicationinformation sent by a network device, where the BWP switching indicationinformation is used to instruct the UE to use a second BWP.

The processing unit 602 is further configured to: continue to performthe random access procedure on the first BWP, or stop performing therandom access procedure on the first BWP, and perform the random accessprocedure on the second BWP.

The random access apparatus 600 can implement at least one of theforegoing method embodiments. For details, refer to the foregoing methodembodiments, and details are not described in this application again.

It should be understood that division of the units is merely logicalfunction division. In actual implementation, the units may be all orpartially integrated into a physical entity, or may be physicallyseparate. In addition, the units all may be implemented by softwareinvoked by a processing element, or all may be implemented by hardware,or some units may be implemented by software invoked by a processingelement, and some units are implemented by hardware. For example, theprocessing unit may be a separately disposed processing element, may beimplemented by being integrated into a chip, or may be stored in amemory in a form of a program, and a processing element invokes theprogram and executes the function of the unit. Implementations of theother units are similar. In addition, all or some of the units may beintegrated together, or may be implemented independently. The processingelement may be an integrated circuit and has a signal processingcapability. In an implementation process, steps in the foregoing methodsor the foregoing units can be implemented by using a hardware integratedlogical circuit in the processing element, or by using instructions in aform of software. In addition, the receiving unit is a unit configuredto control receiving, and may receive information by using a receivingapparatus of the terminal device or the network device, for example, anantenna and a radio frequency apparatus. The sending unit is a unitconfigured to control sending, and may send information by using asending apparatus of the terminal device or the network device, forexample, an antenna and a radio frequency apparatus.

For example, the units may be one or more integrated circuits configuredto implement the foregoing method, for example, one or more applicationspecific integrated circuits (application specific integrated circuit,ASIC), one or more digital signal processors (digital signal processor,DSP), or one or more field programmable gate arrays (field programmablegate array, FPGA). For another example, when a particular unit isimplemented by the processing element invoking a program, the processingelement may be a general-purpose processor, for example, a centralprocessing unit (central processing unit, CPU) or another processor thatcan invoke the program. For another example, the units may be integratedtogether, and implemented in a form of a system on chip(system-on-a-chip, SOC).

Based on the foregoing embodiment, this application further providesuser equipment, capable of implementing at least one of the foregoingmethod embodiments. Referring to FIG. 7, the user equipment 700 includesa transceiver 701, a processor 702, and a memory 703.

The memory 703 is configured to store a computer executable instruction.When the processor 702 executes the computer executable instruction, theuser equipment 700 performs one of the foregoing method embodiments.

It may be understood that the random access apparatus in the embodimentshown in FIG. 6 may be implemented by the user equipment 700 shown inFIG. 7. A structure of the user equipment 700 does not constitute alimitation to the embodiments of this application.

The user equipment 700 can implement at least one of the foregoingmethod or apparatus embodiments. For details, refer to the foregoingmethod and apparatus embodiments, and details are not described in thisapplication again.

The processor 702 may be a central processing unit (central processingunit, CPU), a network processor (network processor, NP), a hardwarechip, or any combination thereof. The memory may include a volatilememory (volatile memory) such as a random access memory (random accessmemory, RAM), or the memory may include a non-volatile memory(non-volatile memory) such as a read-only memory (read-only memory,ROM), a flash memory (flash memory), a hard disk drive (hard disk drive,HDD), or a solid-state drive (solid-state drive, SSD), or the memory mayinclude a combination of the foregoing types of memories.

It should be understood that the term “and/or” in this specificationdescribes only an association relationship for describing associatedobjects and represents that three relationships may exist. For example,A and/or B may represent the following three cases: Only A exists, bothA and B exist, and only B exists. In addition, the character “/” in thisspecification generally indicates an “or” relationship between theassociated objects.

It should be understood that in various embodiments of this application,sequence numbers of the foregoing processes do not mean executionsequences. The execution sequences of the processes should be determinedaccording to functions and internal logic of the processes, and shouldnot be construed as any limitation to the implementation processes ofthe embodiments of the present invention.

Mutual reference may be made to related parts in the method embodimentsof this application. The apparatuses provided in the apparatusembodiments are configured to perform the methods provided in thecorresponding method embodiments. Therefore, for the apparatusembodiments, refer to the related parts in the related methodembodiments for understanding.

Structural diagrams of the apparatuses in the apparatus embodiments ofthis application merely show simplified designs of the correspondingapparatuses. In actual application, the apparatus may include anyquantities of transmitters, receivers, processors, memories, and thelike, to implement functions or operations performed by the apparatusesin the apparatus embodiments of this application, and all apparatusesthat can implement this application fall within the protections scope ofthis application.

Names of message/frame/indication information, modules, units, or thelike in the embodiments of this application are merely an example, andanother name may be used provided that the message/frame/indicationinformation, modules, or units have same functions.

A person skilled in the art should understand that the embodiments ofthis application may be provided as a method, a system, or a computerprogram product. Therefore, the embodiments of this application may usea form of hardware only embodiments, software only embodiments, orembodiments with a combination of software and hardware. In addition,the embodiments of this application may use a form of a computer programproduct that is implemented on one or more computer-usable storage media(including but not limited to a disk memory, a CD-ROM, and an opticalmemory) that include computer-usable program code.

The embodiments of this application are described with reference to theflowcharts and/or block diagrams of the method, the device (system), andthe computer program product according to the embodiments of thisapplication. It should be understood that computer program instructionsmay be used to implement each process and/or each block in theflowcharts and/or the block diagrams and a combination of a processand/or a block in the flowcharts and/or the block diagrams. Thesecomputer program instructions may be provided for a general-purposecomputer, a dedicated computer, an embedded processor, or a processor ofany other programmable data processing device to generate a machine, sothat the instructions executed by a computer or a processor of any otherprogrammable data processing device generate an apparatus forimplementing a specific function in one or more processes in theflowcharts and/or in one or more blocks in the block diagrams.

These computer program instructions may be stored in a computer readablememory that can instruct the computer or any other programmable dataprocessing device to work in a specific manner, so that the instructionsstored in the computer readable memory generate an artifact thatincludes an instruction apparatus. The instruction apparatus implementsa specific function in one or more processes in the flowcharts and/or inone or more blocks in the block diagrams.

These computer program instructions may be loaded onto a computer oranother programmable data processing device, so that a series ofoperations and steps are performed on the computer or the anotherprogrammable device, to generate computer-implemented processing.Therefore, the instructions executed on the computer or the anotherprogrammable device provide steps for implementing a specific functionin one or more processes in the flowcharts and/or in one or more blocksin the block diagrams.

Obviously, a person skilled in the art can make various modificationsand variations to embodiments of this application without departing fromthe spirit and scope of this application. This application is intendedto cover these modifications and variations of the embodiments of thisapplication provided that they fall within the scope of the claims ofthis application and their equivalent technologies.

What is claimed is:
 1. A random-access method implemented by a userequipment (UE), wherein the random-access method comprises: working on afirst bandwidth part (BWP), wherein the first BWP is a currently activeBWP; performing a first random-access procedure on an initial BWP whenthe first BWP does not meet a first condition for performing the firstrandom-access procedure, wherein the initial BWP is from a networkdevice in system information; performing the first random-accessprocedure on the first BWP when the first BWP meets the first condition;receiving BWP switching indication information from the network devicewhen the UE performs the first random-access procedure on the first BWP,wherein the BWP switching indication information instructs the UE to usea second BWP; choosing, in response to receiving the BWP switchingindication information, whether to continue to complete the firstrandom-access procedure on the first BWP or to switch to the second BWPto initiate to a second random-access procedure on the second BWP; andeither continuing to perform the first random-access procedure on thefirst BWP or stopping performing the first random-access procedure onthe first BWP and initiating the second random-access procedure on thesecond BWP.
 2. The random-access method of claim 1, further comprising:identifying that the initial BWP meets the first condition; andperforming, in response to the initial BWP meeting the first condition,the first random-access procedure on the initial BWP.
 3. Therandom-access method of claim 2, wherein the first BWP comprises a firstuplink (UL) BWP or a first downlink (DL) BWP, wherein the second BWPcomprises a second UL BWP or a second DL BWP, wherein the BWP switchingindication information instructs the UE to use the second UL BWP, thesecond DL BWP, or both the second UL BWP and the second DL BWP, andwherein the BWP switching indication information further instructs theUE to switch the first UL BWP, the first DL BWP, or the first UL BWP andthe first DL BWP.
 4. The random-access method of claim 1, furthercomprising: identifying that the second BWP meets the first condition;and initiating, in response to the second BWP meeting the firstcondition, the second random-access procedure on the second BWP.
 5. Therandom-access method of claim 1, wherein meeting the first conditioncomprises identifying that a resource used for random access isavailable.
 6. The random-access method of claim 1, wherein not meetingthe first condition comprises identifying that a resource used forrandom access is not configured.
 7. The random-access method of claim 1,wherein performing the first random-access procedure on the first BWPcomprises: skipping deactivating the first BWP; keeping the first BWPactivated; or stopping a bandwidth part inactivity timer that maintainsthe first BWP.
 8. The random-access method of claim 1, whereininitiating the second random-access procedure on the second BWPcomprises: setting a power ramping counter to a first initial value; orsetting a backoff parameter to a second initial value.
 9. Therandom-access method of claim 1, wherein the first BWP comprises a firstuplink (UL) BWP or a first downlink (DL) BWP, wherein the second BWPcomprises a second UL BWP or a second DL BWP, wherein the BWP switchingindication information instructs the UE to use the second UL BWP, thesecond DL BWP, or both the second UL BWP and the second DL BWP, andwherein the BWP switching indication information further instructs theUE to switch the first UL BWP, the first DL BWP, or the first UL BWP andthe first DL BWP.
 10. A user equipment (UE), comprising: a memoryconfigured to store computer-executable instructions; and a processorcoupled the memory and configured to execute the instructions to causethe UE to: work on a first bandwidth part (BWP), wherein the first BWPis a currently active BWP; enable the UE to perform the firstrandom-access procedure on an initial BWP when the first BWP does notmeet a first condition for performing the first random-access procedure,wherein the initial BWP is from a network device in system information;enable the UE to perform the first random-access procedure on the firstBWP when the first BWP meets the first condition; receive BWP switchingindication information from the network device when the UE performs thefirst random-access procedure on the first BWP, wherein the BWPswitching indication information instructs the UE to use a second BWP;choose, in response to receiving the BWP switching indicationinformation, whether to continue to complete the first random-accessprocedure on the first BWP or to switch to a second BWP to initiate to asecond random-access procedure on the second BWP; and either enable theUE to continue to perform the first random-access procedure on the firstBWP or enable the UE to stop performing the first random-accessprocedure on the first BWP and initiate the second random-accessprocedure on the second BWP.
 11. The UE of claim 10, wherein theprocessor is further configured to execute the instructions to cause theUE to: identify that the initial BWP meets the first condition; andinitiate, in response to the initial BWP meeting the first condition, athird random-access procedure on the initial BWP.
 12. The UE of claim10, wherein the processor is further configured to execute theinstructions to cause the UE to: identify that the second BWP meets thefirst condition; and initiate, in response to the second BWP meeting thefirst condition, the second random-access procedure on the second BWP.13. The UE of claim 10, wherein when identifying that the first BWPmeets the first condition, the processor is further configured toexecute the instructions to cause the UE to identify that a resourceused for random access is available.
 14. The UE of claim 10, whereinwhen identifying that the first BWP does not meet the first condition,the processor is further configured to execute the instructions to causethe UE to identify that a resource used for random access is notconfigured.
 15. The UE of claim 10, wherein when performing therandom-access procedure on the first BWP, the processor is furtherconfigured to execute the instructions to cause the UE to: skipdeactivating the first BWP; keep the first BWP activated; or stop abandwidth part inactivity timer that maintains the first BWP.
 16. The UEof claim 10, wherein the first BWP comprises a first uplink (UL) BWP ora first downlink (DL) BWP, wherein the second BWP comprises a second ULBWP or a second DL BWP, wherein the BWP switching indication informationinstructs the UE to use the second UL BWP, the second DL BWP, or boththe second UL BWP and the second DL BWP, and wherein the BWP switchingindication information further instructs the UE to switch the first ULBWP, the first DL BWP, or the first UL BWP and the first DL BWP.
 17. Acomputer program product comprising computer-executable instructionsstored on a non-transitory computer-readable medium that, when executedby a processor, cause a user equipment (UE) to: work on a firstbandwidth part (BWP), wherein the first BWP is a currently active BWP;perform a first random-access procedure on an initial BWP when the firstBWP does not meet a first condition for performing the firstrandom-access procedure, wherein the initial BWP is from a networkdevice in system information; perform the first random-access procedureon the first BWP when the first BWP meets the first condition; receiveBWP switching indication information from the network device when the UEperforms the first random-access procedure on the first BWP, wherein theBWP switching indication information instructs the UE to use a secondBWP; choose, in response to receiving the BWP switching indicationinformation, whether to continue to complete the first random-accessprocedure on the first BWP or to switch to a second BWP to initiate to asecond random-access procedure on the second BWP; and either continue toperform the first random-access procedure on the first BWP or stopperforming the first random-access procedure on the first BWP andinitiate the second random-access procedure on the second BWP, whereinthe UE chooses whether to continue to complete the first random-accessprocedure on the first BWP or to switch to the second BWP to initiatethe second random-access procedure.
 18. The computer program product ofclaim 17, wherein the computer-executable instructions further cause theUE to: identify that the initial BWP meets the first condition; andperform, in response to the initial BWP meeting the first condition, thefirst random-access procedure on the initial BWP.
 19. The computerprogram product of claim 17, wherein the computer-executableinstructions further cause the UE to: identify that the second BWP meetsthe first condition; and initiate, in response to the second BWP meetingthe first condition, the second random-access procedure on the secondBWP.
 20. The computer program product of claim 17, wherein whenidentifying that the first BWP meets the first condition, thecomputer-executable instructions further cause the UE to identify that aresource used for random access is available.